Amorphous polyether glycols based on bis-substituted oxetane monomers

ABSTRACT

This invention is directed to mono- and bis-substituted oxetane monomers having fluorinated alkoxymethylene side chains, hydroxy-terminated prepolymers derived from these mono- and bis-substituted oxetane monomers and tetrahydrofuran (THF), and polymers produced from these prepolymers, as well as the synthesis processes associated with each, and the use of the monomers, prepolymers and ultimate polymers, both directly and as components of numerous compositions.

This application is a continuation-in-part of and claims the benefit ofU.S. Provisional Application No. 60/144,375, filed Jul. 16, 1999thedisclosure of which is incorporated by reference.

FIELD OF INVENTION

The present invention relates generally to amorphous polyether glycolsbased on bis-substituted oxetane monomers. More particularly, thepresent invention relates to hydroxy-terminated prepolymer compositionsand to the polymers derived therefrom, oxetane monomers havingbis-substituted pendant fluorinated alkoxymethylene groups as theprepolymer precursors, methods for preparing the precursor monomers andmethods for polymerizing the prepolymers to form fluorinated elastomers.The hydroxyterminated prepolymers have a polyether backbone and areuseful, inter alia, for the preparation of elastomers, thermosetplastics and coatings. These compositions exhibit hydrophobicproperties, very low surface energies, low glass transitiontemperatures, low dielectric constants, high abrasion resistance andtear strength, low coefficient of friction, high adhesion and lowrefractive indices.

BACKGROUND OF THE INVENTION

Fluorinated polymers enjoy widespread use as hydrophobic, oleophobiccoatings. These materials exhibit excellent environmental stability,high hydrophobicity, low surface energy and a low coefficient offriction, and are used in a number of applications ranging from nonstickfrying pans to optical fiber cladding. Most fluoropolymers, however, areplastics that are difficult to process, difficult to apply and areunsuitable as coatings for flexible substrates due to their highrigidity. One example of a widely used fluorinated material is TEFLON™,a polytetrafluoroethylene. TEFLON™ is difficult to process in that it isa rigid solid that must be sintered and machined into its finalconfiguration. Commercial application of TEFLON™ as a coating iscomplicated by its poor adhesion to substrates and its inability to forma continuous film. As TEFLON™ is insoluble, application of a TEFLON™film involves spreading a thin film of powdered TEFLON™ onto the surfaceto be coated and, thereafter, the powdered TEFLON™ is sintered in placeresulting in either an incomplete film or a film having many voids. AsTEFLON™ is a hard inflexible plastic, a further limitation is that thesubstrate surface must be rigid, otherwise the TEFLON™ will either crackor peel off.

A limited number of commercial fluoropolymers, such as Viton, possesselastomeric properties. However, these materials have relatively highsurface energies (as compared to TEFLON™), poor abrasion resistance andtear strength, and their glass transition temperatures are still highenough (greater than 0° C. for Viton) to significantly limit their usein low-temperature environments.

Accordingly, there is a need for fluoroelastomers having hydrophobicproperties, surface energies and coefficients of friction at leastequivalent to the fluorinated plastics (such as TEFLON™). Further, suchfluoroelastomers must have high adhesion, high abrasion resistance andtear strength, low index of refraction and low glass transitiontemperatures so that they are suitable for any foreseeably lowtemperature environmental use. In addition, there is a need forfluoroelastomers that are easily produced in high yields and easy touse.

The most important criteria in the development of release (i.e.,nonstick), high lubricity coatings is the minimization of the freesurface energy of the coating. Free surface energy is a measure of thewettability of the coating and defines certain critical properties, suchas hydrophobicity and adhesive characteristics of the material. For mostpolymeric surfaces, the surface energy can be expressed in terms of thecritical surface tension of wetting ã_(C). For example, the surfaceenergy of TEFLON™ (represented by ã_(C)) is 18.5 ergs/cm², whereas thatof polyethylene is 31 ergs/cm². Consequently, coatings derived fromTEFLON™ are more hydrophobic and nonstick than those derived frompolyethylene. A substantial amount of work has been done by the coatingindustry to develop coatings having surface energies lower than orcomparable to TEFLON™, while at the same time exhibiting superioradhesion characteristics.

The literature teaches that in order to prepare coatings having thedesirable low surface energy, the surface of the coating must bedominated by —CF₃ groups. Groups such as —CF₂—H and —CFH₂ increase thesurface energy of the material. The importance of the number of fluorineatoms in the terminal group (i.e., the group present on the surface) wasdemonstrated by Zisman, et al., J. Phys. Chem., 57:622 (1953); Zisman,et al., J. Colloid Sci., 58:236 (1954); and Pittman, et al., J. PolymerSci., 6:1729 (1968). It was found that materials with terminal —CF₃groups exhibited surface energies in the neighborhood of 6 ergs/cm²,whereas similar materials with terminal —CF₂H groups exhibited values inthe neighborhood of 15 ergs/cm², i. e., more than twice the value forthe material with terminal —CF₃ groups. TEFLON™ incorporates thefluorine moieties on the polymer backbone and does not contain pendant—CF₃ groups. Consequently, TEFLON™ does not exhibit surface energies aslow as polymers having terminal perfluorinated alkyl side chains.

A critical requirement in the production of an elastomer is that theelastomer have large zones, or “soft segments,” where little or nocrosslinking occurs and where the polymer conformation is such thatthere is little or no compaction of the polymer as a result ofcrystallization. Intermediate of these soft zones are “hard blocks,”where there may be significant hydrogen bonding, crosslinking andcompaction of the polymer. It is this alternating soft block and hardblock that give the polymer its elastomeric properties. The longer thesoft segment, the more elastic the elastomer.

Falk, et al. (U.S. Pat. No. 5,097,048) disclose the synthesis ofbis-substituted oxetane monomers having perfluoro-terminated alkyl groupside chains from bis-haloalkyl oxetanes, the glycols havingperfluoro-terminated alkyl group side chains derived therefrom,including related thiol and amine linked glycols and dimer diols. Mostof the fluorinated side chains are attached to the glycol unit by athio, an amine or a sulfonamide linkage. Only a few examples describeglycols having perfluoro-terminated alkoxymethylene side chains;however, such glycols are crystalline materials.

Falk, et al. (EP 03 48 350) report that their process yieldsperfluoro-terminated alkoxymethylene neopentyl glycols composed of amixture of (1) approximately 64% of a bis-substitutedperfluoro-terminated alkyl neopentyl glycol, and (2) approximately 36%of a mono-substituted perfluoro-terminated alkyl neopentyl glycolproduct with a pendant chloromethyl group. Evidently, themono-substituted product results from incomplete substitution of thesecond chloride on the bis-chloroalkyl oxetane starting material.Consequently, as noted from the Zisman and Pittman work described above,the presence of the —CH₂Cl as a side chain significantly increases thesurface energy of the coatings made from these polymers, therebyreducing the hydrophobicity and oleophobicity of the coatings.

Falk, et al. U.S. Pat. No. 5,045,624) teaches preparation of dimers withfluorinated side chains having thio linkages, but not of dimers withfluorinated ether side chains. This is because the synthesis route usedby Falk, et al. for preparing dimers with thio linkages cannot be usedfor the synthesis of dimers with ether linkages. In other words, Falk,et al. do not teach preparation of long chain polyethers withfluorinated ether side chains.

Falk, et al. (U.S. Pat. No. 4,898,981) teaches incorporation of theirbis-substituted glycols into various foams and coatings to impart thedesired hydrophobicity and oleophobicity. Classic polyurethane chemistryshows that while a plastic may form by reaction of Falk's glycols withdiisocyantes, elastomers cannot form since there is no long chain softsegment. Such a soft segment is needed for the formation of anelastomer. Since the compounds of Falk, et al. are only one or twomonomer units long, they are clearly too short to function as a softsegment for the formation of a polyurethane elastomer. In Falk, et al.,the fluorinated glycol and isocyanate segments alternate, with thefluorinated glycol segments, being nearly the same size as theisocyanate segments. It is well known to those of skill in the art thatsuch a polymer structure will not yield elastomers.

None of the Falk, et al. references teach or show a homoprepolymer orcoprepolymer made from bis-perfluoro-terminated alkoxymethyleneoxetanes, nor polyurethanes derived therefrom or from the correspondingglycols. All of their polyurethanes are made directly from thethiol-linked monomers and dimers and not via a prepolymer intermediate.In the examples provided in Falk, et al. U.S. Pat. No. 5,045,624),particularly where the perfluoro-terminated side chains are large andfor all of the dimers, all have thiol linkages, i.e., no ether sidechains are shown. The polyurethanes disclosed by Falk, et al. (U.S. Pat.No. 4,898,981) are made from the perfluoro-terminated alkylthioneopentyl glycol. However, Falk, et al. (U.S. Pat. No. 5,097,048) inExample 12, show a polyether prepolymer prepared from a bis-substitutedperfluoroalkylthio oxetane. The prepolymer obtained was a white waxysolid, clearly not an elastomer. No characterization as to the nature ofthe end groups, polydispersity, equivalent weights, etc. of the waxysolid was given. Absent such a characterization, it is unknown whetherthe material of Falk, et al. may be further reacted with an isocyanateto produce a polyurethane polymer. No examples of the preparation of apolymer from any prepolymer is given.

Vakhlamova (Chem. Abst. 89:110440p) teaches the synthesis of oxetanecompounds substituted at the number 3 carbon of the oxetane with—CH₂O—CH₂—CF₂—CF₂—H groups. The terminal alkyl portion of thissubstituent is thus: —CF₂CF₂—H, wherein the terminal or omega carbonbears a hydrogen atom. As discussed above, the Zisman and Pittman workshows that the presence of the hydrogen significantly increases thesurface energy of the polymer derived from these monomers. Falk, et al.(U.S. Pat. No. 5,097,048) also recognizes that surface energy increaseswith the hydrogen atom on the terminal carbon by stating that“fluoroalkyl compounds which are terminally branched or containomega-hydrogen atoms do not exhibit efficient oil repellency.” Further,Vakhlamova focuses on the bis-substituted monomer as he hydrolyzes themonomer and then polymerizes the resultant monomeric glycol.

A characteristic of the polymers formed from the polymerization of thebis-substituted oxetanes of Falk, et al., and the other proponents ofbis-substituted oxetanes is that the resulting products are crystallinesolids. The bis-side chains are highly ordered and symmetric.Consequently, they pack efficiently to form a crystalline structure. Forexample, a prepolymer prepared from 3,3-bis-(chloromethyl)oxetane is acrystalline solid that melts in the neighborhood of 220° C. Thissignificantly affects the commercial use of these polymers since eitheror both mixing and elevated temperatures will be required in order todissolve or melt the Falk, et al. polymer for further polymerization orapplication.

As such, to date, the polymerization of the bis-substitutedperfluorinated alkoxymethylene oxetanes has not resulted in usefulmaterials. The polymers derived from the bis-substitutedperfluoroalkylthiol oxetanes are waxy solids and will not function as asoft segment in the preparation of commercially useful elastomers andcoatings. Further, the ability of a bis-substituted oxetane monomer tohomopolymerize appears to be dependent upon the nature of the side chainat the 3-carbon with no assurance that polymerization will occur, thedifficulty of polymerization apparently being due to the stericinterference by the side chains. Polymerization, and the products ofpolymerization, of the bis-substituted monomer accordingly areunpredictable and inconsistent.

U.S. Pat. Nos. 5,654,450, 5,668,251, 5,650,483, 5,668,250 and 5,703,194,all of which have issued to Malik, et al., disclose fluorinatedelastomers and a production strategy therefor, beginning with apremonomer production process that is easy and inexpensive, to producean asymmetrical mono-haloalkyl methyl oxetane premonomer, which uponfurther reaction produces an oxetane monomer having a single fluorinatedside chain, which mono-substituted fluorinated monomer is capable ofhomopolymerization and copolymerization to produce an essentiallynon-crosslinked soft segment, difunctional, linear, asymmetricprepolymer for further reaction to produce fluorinated elastomers andthermoset plastics, resins and coatings having hydrophobic properties,low surface energy, very low glass transition temperatures, lowdielectric constants, high abrasion resistance and tear strength, highadhesion and low refractive indices.

The contributions of U.S. Pat. Nos. 5,654,450, 5,668,251, 5,650,483,5,668,250 and 5,703,194 have resulted in very useful fluorinatedelastomers and methods for their preparation. However, it would beadvantageous if bis-substituted fluorinated oxetane monomers could behomopolymerized and copolymerized to produce essentiallynon-crosslinked, difunctional, linear, asymmetric prepolymers that, inturn, could be further reacted to produce fluorinated elastomers andthermoset plastics, resins and coatings having useful properties, a goalwhich researchers have not yet achieved despite great efforts in thisarea. The present invention achieves this and other goals.

SUMMARY OF THE INVENTION

Prior to the present invention, the use of bis-substituted fluorinatedoxetane monomers (i.e., bis-substituted FOX monomers) in the synthesisof fluoroelastomers has been limited due to the highly crystallinenature of the polymer formed from these symmetrical monomers. However,it has been discovered that this problem can be overcome bycopolymerizing the bis-substituted fluorinated oxetane monomers withmono-substituted fluorinated oxetane monomers and/or nonfluorinatedoxetane monomers, such as tetrahyrofuran (“THF”), to produce amorphouspolyether glycols. Such glycols can be incorporated into a polymermatrix to produce an elastomer which, in turn, can be used for a varietyof applications including, for example, anti-graffiti coatings, wallpaper coatings, automotive coatings, fouling release coatings for shiphulls, pyrotechnic applications, etc. In addition to lowering the costof the raw materials, the present invention provides materials havinghigher amounts of fluorine at the surface, thereby increasing theperformance characteristics of poly(FOX) coatings.

As such, in one aspect, the present invention provideshydroxy-terminated polyether prepolymers having asymmetric,alkoxymethylene side chains with terminal perfluorinated alkyl groups.In one embodiment, the prepolymers comprise a monomeric unit having thefollowing general formula:

In the above formula, each n is independently selected and is 1 to 3;R_(f) ¹ and R_(f) ² are independently selected from the group consistingof linear perfluorinated alkyls, linear perfluorinated isoalkyls,branched chain perfluorinated alkyols, branched perfluorinatedisoalkyls, the perfluorinated alkyls and isoalkyls having from 1 toabout 20 carbon atoms, and oxaperfluorinated polyethers having from 4 toabout 60 carbon atoms; and x is 1 to about 250 and, more preferably, 2to about 100. It is noted that R_(f) ¹ and R_(f) ² are selected so thatthey are different and have a more or less random placement along theprepolymer chain.

In another embodiment, the prepolymers comprise a mixture of monomericunits have the following general formulae:

In the above formula, each n is independently selected and is 1 to 3; Ris selected from the group consisting of methyl and ethyl; R_(f) ¹,R_(f) ² and R_(f) ³ are independently selected from the group consistingof linear fluorinated alkyls, linear fluorinated isoalkyls, branchedchain fluorinated alkyls, branched fluorinated isoalkyls, thefluorinated alkyls and isoalkyls having from 1 to 20 carbon atoms, andoxaperfluorinated polyethers having from 4 to about 60 carbon atoms; xis about 1 to about 250 and, more preferably, 2 to about 100; and y isabout 1 to about 250 and, more preferably, 2 to about 100. Typically,the ratio of di- to mono-substituted monomers, i.e., the ratio of x toy, is from about 95:5 to about 5:95, more preferably about 70:30 and,even more preferably, about 50:50, with a DP of about 1 to about 250and, more preferably, of about 5 to about 100.

In another aspect, the present invention provides a hydroxy-terminatedpolyether coprepolymer having alkoxymethylene side chains with terminalperfluorinated alkyl groups and a backbone composed of FOX monomersegments and of tetrahydrofuran (THF) segments. In one embodiment, theFOX/THF coprepolymer comprises a mixture of monomeric units having thefollowing general formulae:

In the above formulae, n is independently selected and is 1 to 3; R_(f)¹ and R_(f) ² are independently selected from the group consisting oflinear perfluorinated alkyl groups having 1-20 carbons, branchedperfluorinated alkyl groups having 1-20 carbons and oxaperfluorinatedpolyethers having from about 4-60 carbons; x is about 1 to about 250and, more preferably, 2 to about 100; and z is about 1 to about 250 and,more preferably, 1 to 100. Typically, the ratio of di- tomono-substituted monomers, i.e., the ratio of x to z, is from about 1:99to about 99:1, with a DP of about 1 to about 250 and, more preferably,of about 5 to about 100. Moreover, typically, the molecular weight(M_(n)) of the FOX/THF coprepolymers ranges from about 2,000 to about50,000 and, more preferably, from about 2,000 to about 15,000; and theT_(g) is less than −20° C.

In another embodiment, the FOX/THF coprepolymers of the presentinvention comprise a mixture of monomeric units having the followinggeneral formulae:

In the above formulae, each n is independently selected and is 1 to 3; Ris selected from the group consisting of methyl and ethyl; R_(f) ¹,R_(f) ² and R_(f) ³ are independently selected from the group consistingof linear perfluorinated alkyl groups having 1-20 carbons, branchedperfluorinated alkyl groups having 1-20 carbons and oxaperfluorinatedpolyethers having from about 4-60 carbons; x is 1 to about 250 and, morepreferably, 2 to about 100; y is 1 to about 250 and, more preferably, 2to about 100; and z is 1 to about 250 and, more preferably, 1 to about100. Typically, such FOX/THF coprepolymers have a DP of about 1 to about250 Moreover, typically, the molecular weight (M_(n)) of the FOX/THFcoprepolymers ranges from about 2,000 to about 50,000 and, morepreferably, from about 2,000 to about 15,000; and the T_(g) is less than−20° C.

The foregoing prepolymers and coprepolymers can be used, inter alia, ascomponents in coating compositions, resins, lubricants and oils, whichimpart hydrophobic properties, low surface energies, low coefficient offriction, very low glass transition temperatures, low dielectricconstants, high abrasion resistance and tear strength, high adhesion andlow refractive indices to such coating, resins, lubricants and oils.

In another aspect, the present invention provides fluorinated elastomersand thermoset plastics having fluorinated alkoxymethylene side chainsand having good hydrophobic properties, low surface energies, very lowglass transition temperatures, low dielectric constants, high abrasionresistance and tear strength, high adhesion and low refractive indices.In one embodiment, the fluorine-containing thermoplastic polyurethaneelastomer of this invention comprises a mixture of monomeric unitshaving the following general formulae:

In the above formula, n is independently selected and is 1 to 3; R_(f) ¹and R_(f) ² are independently selected from the group consisting oflinear and branched perfluorinated alkyls having 1-20 carbon atoms, andoxaperfluorinated polyethers having from about 4-20 carbon atoms; R¹ isa divalent hydrocarbyl radical; x is 1 to about 250 and, morepreferably, 2 to about 100; and w is 1 to about 50 and, more preferably,1 to about 5. It is noted that R_(f) ¹ and R_(f) ² are selected suchthat they are different. Examples of suitable divalent hydrocarbylradicals include, but are not limited to, the following structures:

In another embodiment, the fluorine-containing thermoplasticpolyurethane elastomer of this invention comprises a mixture ofmonomeric units having the following general formulae:

In the above formula, n is independently selected and is 1 to 3; R isselected from the group consisting of methyl and ethyl; R_(f) ¹, R_(f) ²and R_(f) ³ are independently selected from the group consisting oflinear and branched perfluorinated alkyls having 1-20 carbon atoms, andoxaperfluorinated polyethers having from about 4-20 carbon atoms; R¹ isa divalent hydrocarbyl radical; x is 1 to about 250 and, morepreferably, 2 to about 100; y is 1 to about 250 and, more preferably, 2to about 100; and w is 1 to about 50 and, more preferably, 1 to about 5.

The fluorinated elastomers and plastics of the present invention areuseful as fouling and ice release coatings, drag reduction coatings,moisture barrier coatings; catheters; artificial prosthesis components,such as joints, hearts, and valves; contact lenses; intraocular lenses;films, paints; adhesives; nontransfer cosmetics; water repellentcoatings; oil/stain resistant coatings; incendiary binders; lubricants,and the like.

In addition, the present invention provides the synthesis processesassociated with the monomers, prepolymers and polymer compositions, andthe use of the monomers, prepolymers and ultimate polymers, bothdirectly and as components of numerous compositions.

Other features, objects and advantages of the invention and itspreferred embodiments will become apparent from the detailed descriptionwhich follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a summary of the polymerization reaction of FOX monomers bycationic ring-opening reaction.

DEFINITIONS

“Aprotic Solvent,” as used herein, refers to a solvent that does notdonate a proton.

“BrMMO,” as used herein, refers to 3-bromomethyl-3-methyloxetane.

“Contact Angle,” as used herein, refers to the obtuse or internal anglebetween the surface of a liquid and the surface of an object in contactwith the liquid. A high contact angle corresponds to highhydrophobicity.

“FOX Copolymerization,” as used herein refers to the reaction of a FOXmonomer with either a different FOX monomer or a nonfluorinated monomerto produce a FOX coprepolymer.

“DSC,” as used herein, is the acronym for a differential scanningcalorimeter, a device used for determining a compounds glass transitiontemperature.

“Elastomer,” as used herein, refers to a polymeric material, such asrubber, which can be stretched under low stress to at least twice itsoriginal length and, upon immediate release of the stress, will returnwith force to its approximate original length.

“FOX,” as used herein, is the acronym for Fluorinated OXetane. As usedin the disclosure of this invention the term “FOX” is normally precededby a number; e.g., 3-FOX, 7-FOX, etc. The numerical designationindicates the number of fluorine moieties on the single fluorinated sidechain on the 3-carbon of the FOX monomer.

“GLC,” as used herein, is the acronym for gas-liquid chromatography. Adevice and method used as a separation technique to determine purity andpercent conversion of the starting materials.

“GPC,” as used herein, is the acronym for gel permeation chromatography.A device and method used to determine molecular weight.

“HMMO,” as used herein, is the acronym for3-hydroxymethyl-3-methyloxetane, an intermediate in the production ofthe arylsulfonate oxetane remonomer.

“FOX Homoploymerization,” as used herein, refers to the reaction of aFOX monomer with itself to produce a FOX homoprepolymer.

“Hydrophobicity,” as used herein, refers to the degree to which asubstance lacks an affinity for, or repels, or fails to absorb water.

“Lewis Acid,” as used herein, refers to a substance that can accept anelectron pair from a base. For example, AlCl₃ and BF₃ are Lewis acids.

“Mono-substituted Oxetane,” as used herein, refers broadly to a non-bissubstituted oxetane compound. More specifically, it refers to thepremonomers (e.g. 3-halomethyl-3-methyloxetane) and FOX monomers of thisinvention where the 3-carbon of the oxetane ring is substituted withonly one fluorinated side chain and the other 3-carbon side group is anonfluorinated moiety, e.g., a methyl or ethyl group.

“Bis-substituted Oxetane,” as used herein, refers broadly to a non-monosubstituted oxetane compound. More specifically, it refers to thepremonomers (e.g., 3,3-bis-halomethyloxetane) and FOX monomers of thisinvention where the 3-carbon of the oxetane ring is substituted with twofluorinated side chains. It is important to note that the twofluorinated side chains can be the same or different.

“FOX Monomer,” as used herein, refers to a mono-substituted orbis-substituted fluorinated oxetane or FOX.

“Phase Transfer Catalyst,” as used herein, refers to a catalyst thateffectuates or mediates reactions in a dual-phase heterogeneous reactionmixture.

“FOX Premonomer,” as used herein, refers to the3-haloalkane-3-methyloxetane compounds or the 3,3-bis-haloalkaneoxetanecompounds that, upon reaction with fluorinated alkoxides, yields the FOXmonomers of this invention.

“FOX Prepolymer,” as used herein, refers to a hydroxy terminated,polyether oligomer comprising from about 1 to about 250 FOX or FOX/THFmonomer units which, upon reaction with a polyisocyanate, will yieldpolyurethane elastomers.

“Tetrahydrofuran,” as used herein, refers to the commercially available5-membered cyclic ether, which is abbreviated THF.

“TME,” as used herein, is the acronym for1,1,1-tris(hydroxymethyl)ethane, the starting material for the BrMMOpremonomer synthesis.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS A. GENERAL OVERVIEW

This invention is directed to mono- and bis-substituted oxetanesmonomers having fluorinated alkoxymethylene side chains,hydroxy-terminated prepolymers derived from these monomers andtetrahydrofuran (THF), and polymers produced from these prepolymers, aswell as the synthesis processes associated with each, and the use of themonomers, prepolymers and ultimate polymers, both directly and ascomponents of numerous compositions.

The monomers, polyether hydroxy-terminated prepolymers and resultingcompositions thereof are particularly useful for the preparation ofpolyurethane elastomers, thermoset plastics and coatings that exhibit awide variety of useful properties including, inter alia, hydrophobicproperties, low surface energies, low glass transition temperatures, lowdielectric constants, high abrasion resistance and tear strength, lowcoefficients of friction, high adhesion and low refractive indices. Moreparticularly, examples of the ways in which the incorporation offluorine into a polymer can alter the properties of the resultingpolymer are set forth below.

1. Thermal stability is increased, thereby extending the upper usetemperature of the polymer and allowing these materials to be processedat higher temperatures without degradation and, thus, making themsuitable for use in environments where other hydrocarbon based polymerscannot be used.

2. Surface energy is decreased, thereby improving the releasecharacteristics of the polymer making it suitable for use as backingsfor adhesive tapes, as release coatings for molds, as fouling releasecoatings for ship hulls, and the like.

3. Refractive index of the resulting polymer is reduced, thereby makingit useful for optical applications, such as contact lenses, intraocularlenses, coatings for optical instruments, cladding for optical fibers,and the like.

4. Coefficient of friction is reduced, thereby improving the lubricityof the coating making it useful in applications such as vehicle seals,windshield wipers, drag reducing coatings for sail boats, airplanes,etc.

5. Hydrophobicity is increased, thereby improving water repellency andmoisture barrier characteristics making the polymer useful forencapsulating electronic devices and as moisture barrier films andcoatings, rain erosion coatings, anticorrosion coatings, etc.

6. Oleophobicity is increased, thereby making the polymer oil repellentand, thus, useful as a stain resistant coating for garments and carpets.

7. Flammability is decreased, thereby improving flame retardency, forexample, on garments coated with the polymer.

8. Environmental stability of the polymer is improved, thereby makingthe polymer more stable when exposed to ultraviolet light and moisture.

As a result of the above beneficial properties, a major application ofthe polymers of the present invention is for nonstick coatings as aresult of the fact that the adhesion properties of the polymers of thisinvention are better than TEFLON™, the surface energy is lower,application is easier, and the applied film is flexible with goodabrasion resistance and tear strength, thereby permitting application toboth flexible and rigid surfaces. Example of suitable applicationsinclude, but are not limited to, anti-fouling coatings, ice releasecoatings, flexible optical fiber cladding, conduit and aqueduct coatingsor linings, surface coatings, anti-graffiti coatings, automotivetop-coat compositions (e.g., car wax), particularly at low temperaturesdue to low glass transition temperatures on the order of −40° C. to −50°C. The low index of refraction and good oxygen permeability, coupledwith the optical clarity of some of the elastomers produced from theprepolymers, make them useful for contact lenses and intraocular lenses.Of course, other uses for elastomers are well known to those of skill inthe art, and the improved properties of the elastomers of this inventionpermit an even wider range of uses.

Bis-substituted, either symmetrically or asymmetrically substituted, areused to produce homo- or coprepolymers characterized as non-crosslinked,asymmetrical, hydroxy-terminated, linear oligomers having from about 10to about 500 carbons and, more preferably, from about 20 to about 200carbons, i.e., FOX prepolymers. These prepolymers are crucial to theproduction of fluorinated elastomers in that they substantially retaintheir integrity in subsequent polymerizing reactions (e.g., reactionswith diisocyanates or polyisocyanates) to provide the soft segmentblocks of the resulting polymers which, in combination with the hardblocks formed during polymerization, produce good elastomers. Althoughprior to the present invention there was no showing of copolymerizationof the bis-substituted FOX monomers with either mono-substituted FOXmonomers or other cylcic ethers to produce prepolymers containing softsegment required for production of elastomers, the processes of thepresent invention readily polymerize bis-substituted FOX monomers withboth mono-substituted FOX monomers and other cylcic ethers. The reactionmechanism of the processes of the present invention produce prepolymersfrom mono- and bis-substituted FOX monomers and other cyclic ethers(e.g., THF) in high yields.

Although the coprepolymers composed of bis-substituted/mono-substitutedFOX comonomers and of FOX/THF comonomers contain fewer fluorine moietiesthan bis-substituted prepolymers, they surprisingly produce polymersthat have similar surface energies to a polymer derived from prepolymershaving two fluorinated side chains. Further, even though the FOX/THFprepolymers of the present invention contain less fluorine than the FOXprepolymers of the present invention, the elastomers produced from theFOX/THF prepolymers surprisingly exhibit surface and physical propertiescomparable to the elastomers produced from the FOX prepolymers.

In addition, a polymerization process has been discovered that virtuallyeliminates the formation of undesirable by-products. The presence ofnonfunctional or monofunctional materials in the prepolymers result incoatings with poor mechanical and surface properties. Consequently,these coatings have limited commercial value. Nonfunctional materials,mainly cyclic tetramers and trimers, are formed during the ring openingpolymerization from chain “back-biting.” Monofunctional materials, onthe other hand, are formed due to counter-ion terminations, such asdiethyl ether and fluoride ion terminations. The processes of thisinvention are unique in their lack of by-product production. Using themethods of the present invention, production of cyclic tetramers andmonofunctional prepolymers are virtually eliminated.

B. MONOMERS

1. Preparation of Mono- and Bis-Substituted FOX Monomers

The mono- and bis-substituted fluorinated alkyloxy-3-methyloxetanemonomers of this invention have the following general formula:

In the above formula, n is 1 to 3, m is 1 (for mono-substituted) or 2(for bis-substituted), R is methyl or ethyl, and R_(f) is a linear orbranched chain fluorinated alkyl and isoalkyl having from 1 to 20carbons, or an oxaperfluorinated polyether having from 4 to about 60carbons.

The FOX monomers of this invention are obtained by reaction of arylsulfonate derivatives of 3-hydroxymethyl-3-methyloxetanes(arylsulfonate-MO), 3,3-hydroxymethyloxetanes (arylsulfonate-BO) or thereaction of mono-substituted 3-haloalkyl-3-methyloxetanes orbis-substituted 3,3-(haloalkyl)oxetanes with fluorinated alkoxides inthe presence of a polar aprotic solvent:

In the above formula, R_(f) is linear or branched chain perfluorinatedalkyl or isoalkyl having from 1 to 20 carbons, or an oxaperfluorinatedpolyether having from 4 to about 60 carbons; and X=Br, Cl, I or an arylsulfonate. Examples of suitable R_(f) groups include, but are notlimited to, —CF₃, —C₂F₅, —C₃F₇ and —C₇F₁₅. It is noted that the numericFOX designation is determined by the number of fluorine atoms in theterminal perfluoroalkyl group of the side chain.

The aryl sulfonate derivatives of the hydroxyalkyloxetanes have thegeneral formula:

In the above formula, m is 1 (for mono-substituted) or 2 (forbis-substituted), R_(a) is a monocyclic aryl having from C₆ to C₁₀carbons, e.g., benzyl, tolyl, xylyl, mesityl or an alkyl, such as —CH₃or —CF₃. The preferred sulfonates are toluene sulfonates, e.g.,p-toluene sulfonate derivatives of 3-hydroxymethyl-3-methyloxetane(HMMO) or 3,3-hydroxymethyloxetane (BHMO).

The fluorinated alkoxides are obtained by the reaction of fluorinatedalcohols with sodium hydride in a suitable solvent such asdimethylformamide:

R_(f)(CH₂)_(n)OH+NaH→Rf(CH₂)_(n)O⁻Na⁺+H₂

The fluorinated alcohols which can be used have the general formula:

R_(f)(CH₂)_(n)OH

In the above formula, n is 1 to 3; and R_(f) is a linear or branchedchain fluorinated alkyl or isoalkyl having from 1 to 20 carbons, or anoxaperfluorinated polyether having from 4 to about 60 carbons. Examplesof suitable fluorinated alcohols include, but are not limited to,trifluoroethanol, heptafluorobutanol, pentadecafluorooctanol,tridecafluorooctanol, and the like. Other useful alcohols includefluorinated alcohols having the following formulas:

In the above formulae, n is 1 to about 3, and x is 1 to about 20.

Although sodium hydride is the preferred base for this reaction, otherbases, such as potassium hydride, potassium t-butoxide, calcium hydride,sodium hydroxide, potassium hydroxide, NaNH₂, n-butyl lithium andlithium diisopropylamide, can also be used. Moreover, although thepreferred solvent for the formation of the alkoxide from these alcoholsis dimethylformamide (DMF), other solvents, such as dimethylacetamide,DMSO and hexamethylene phosphoramide (HMPA), can also be used.

The displacement reaction can be conducted at a temperature ranging fromabout 25° C. to about 150° C. and, more preferably, at a temperatureranging from about 75° C. to about 85° C. At lower temperatures, therate of displacement is slowed down considerably and, thus, is onlymarginally useful for commercial scale-up. At higher temperatures, i.e.,greater than 120° C., the rate of displacement is extremely fast.However, at these higher temperatures, other side reactions, such ashydrolysis reactions, dominate. Thus, the preferred reaction temperatureis less than 120° C.

It is noted that mono-substituted FOX monomers can advantageously bederived from the premonomer 3-bromomethyl-3-methyloxetane (“BrMMO”). Thepreparation of BrMMO and the use of this premonomer to preparemono-substituted FOX monomers are disclosed in U.S. Pat. No. 5,654,450,which issued to Malik, et al. on Aug. 5, 1997, the teachings of whichare incorporated herein by reference.

2. Preferred Process for Synthesis of FOX Monomers

A preferred process for preparing FOX monomers in high yields has beendiscovered that eliminates the use of organic solvents and strong bases,such as NaH. The elimination of organic solvents reduces hazardous wastegeneration and air emissions of volatile organic compounds. The processsteps are as follows:

In the above reaction scheme, R_(f) is a linear or branched chainperfluorinated alkyl or isoalkyl having from 1 to 20 carbons, or anoxaperfluorinated polyether having from 4 to about 60 carbons; and X=Br,Cl or I.

In this process, a mixture of 3-haloalkyl-3-methyloxetane (formono-substituted FOX monomers) or 3,3-(haloalky)oxetane (forbis-substituted FOX monomers), fluoroalcohol, a base, such as sodiumhydroxide or potassium hydroxide, and a phase transfer catalyst areheated in an aqueous medium at a temperature of about 80° to about 85°C. until GLC analysis reveals complete consumption of the startingmaterials. Upon completion of the reaction, the product is recovered byseparation and distillation of the organic phase. The organic phasecontains most of the FOX monomer. The recovered FOX monomer is polymergrade and has a purity normally in excess of 99%. Isolated yields arehigh and range from about 80% to about 90% for the purified FOX monomer.Yields prior to separation and purification exceed 90% for the crudeproduct.

A variety of bases can be used in the above process. Examples ofsuitable bases include, but are not limited to, sodium hydroxide,potassium hydroxide, calcium hydroxide, magnesium hydroxide,tetrabutylammonium hydroxide, etc. In a presently preferred embodiment,sodium hydroxide and potassium hydroxide are used because they arereadily available in large quantities and are relatively inexpensive.

Phase transfer catalysts function by transferring the counterion so thatit is more soluble in the organic phase. A variety of phase transfercatalysts can be used in this process. Examples of suitable phasetransfer catalysts include, but are not limited to, tetramethylammoniumbromide, tetraethylammonium bromide, tetramethylammonium iodide,cetyltributylammonium bromide, crown ethers, glycols, and the like. In apreferred embodiment, tetrabutylammonium bromide is the phase transfercatalyst used due to its relatively low cost and good solubility in bothorganic and aqueous mediums.

The above reaction can be conducted at temperatures as low as 50° C. andas high as 120° C. However, at low temperatures, the rate ofdisplacement is slowed and competing side reactions, such as hydrolysis,start to dominate. At higher temperatures, the rate of displacement isextremely fast, requiring specialized equipment that can handlepressure, thereby making the process uneconomical and unattractive forcommercial scale-up.

C. PREPOLYMERS

The present invention provides the following types of prepolymers:homo-prepolymers where the prepolymer is assembled from onlyasymmetrically bis-substituted FOX monomer; coprepolymers where theprepolymer is assembled from a mixture of symmetrically bis-substitutedFOX monomers and asymmetrically bis-substituted FOX monomers;coprepolymers where the prepolymer is assembled from a mixture ofbis-substituted FOX monomers (either symmetrically, asymmetricallysubstituted or a mixture thereof) and mono-substituted FOX monomers (ora mixture thereof); coprepolymers where the prepolymer is assembled froma mixture of bis-substituted FOX monomers (either symmetrically,asymmetrically substituted or a mixture thereof) and tetrahydrofuran(THF); coprepolymers where the prepolymer is assembled from a mixture ofbis-substituted FOX monomers (either symmetrically substituted,asymmetrically substituted or a mixture thereof) and mono-substitutedFOX monomers (or a mixture thereof) and THF.

One of the main applications of the hydroxy-terminated FOX prepolymersis in the development of hydrophobic, nonstick, low friction materials.The most important criterion in preparation of these materials is theminimization of the surface energy, which is a measure of thewettability of the material and defines critical properties, such as itshydrophobicity and adhesive characteristics.

In order to prepare materials with low surface energies, it is criticalthat the fluoroalkyl groups be present in the side chain and that theterminal carbon of the fluoroalkyl groups be perfluorinated. Theimportance of having fluorine in the side chain, rather than in thepolymer backbone, is demonstrated by comparing the surface energies offluorinated polyacrylates and polytetrafluoroethylene (TEFLONTm). Thesurface energy of TEFLON™, which contains fluorine in the polymerbackbone, is 18.5 ergs/cm². By comparison, the surface energy ofpolyfluoroacrylates, which contain fluorine in the side chains, isbetween 10-12 ergs/cm². Also, fluoroalkyl groups that contain hydrogenor halogen (ie., Cl, Br, I, etc.) on the terminal carbon haveconsiderably higher surface energies than those with the —CF₃ groups.The dependence of surface energy on the surface constitution of typicalorganic materials is illustrated in Table 1.

TABLE 1 SURFACE ENERGIES OF ORGANIC MATERIALS SURFACE CONSTITUTIONERGS/CM² @ 20° C. —CF₃ Close Packed 6 —CF₂H 15 —CF₂— 18 —CH₃ 22 —CH₂— 31—CH₂CHCl— 39 Polyester 43

It has now been discovered that placing the fluorine in the side chain,rather than on the backbone as in TEFLON™, improves surface lubricity,and the resulting prepolymer/elastomer exhibits a surface energy lowerthan a polymer having fluorine just in the backbone. There is, however,a trade-off between having the fluorine on the side chain and having thefluorine on the backbone. More particularly, while an increase inlubricity in achieved by incorporating a fluorinated side chain, thereis a reduction in thermal stability as compared to a polymer havingfluorine only on the backbone, e.g., as in TEFLON™.

1. Hydroxy-Terminated FOX Homo- and Coprepolymers

As discussed above, the present invention provides the following typesof hydroxy-terminated FOX homo- and coprepolymers: homoprepolymers wherethe prepolymer is assembled from only asymmetrically bis-substituted FOXmonomer; coprepolymers where the prepolymer is assembled from a mixtureof symmetrically bis-substituted FOX monomers and asymmetricallybis-substituted FOX monomers; and coprepolymers where the prepolymer isassembled from a mixture of bis-substituted FOX monomers (eithersymmetrically, asymmetrically substituted or a mixture thereof) andmono-substituted FOX monomers (or a mixture thereof). As such, in oneembodiment, the prepolymers comprise a monomeric unit having thefollowing general formula:

In the above formula, each n is independently selected and is 1 to 3;R_(f) ¹ and R_(f) ² are independently selected from the group consistingof linear perfluorinated alkyls, linear perfluorinated isoalkyls,branched chain perfluorinated alkyols, branched perfluorinatedisoalkyls, the perfluorinated alkyls and isoalkyls having from 1 toabout 20 carbon atoms, and oxaperfluorinated polyethers having from 4 toabout 60 carbon atoms; and x is 1 to about 250 and, more preferably, 2to about 100. It is noted that R_(f) ¹ and R_(f) ² are selected so thatthey are different.

In another embodiment, the prepolymers comprise a mixture of monomericunits have the following general formulae:

In the above formula, each n is independently selected and is 1 to 3; Ris selected from the group consisting of methyl and ethyl; and R_(f) ¹,R_(f) ² and R_(f) ³ are independently selected from the group consistingof linear fluorinated alkyls, linear fluorinated isoalkyls, branchedchain fluorinated alkyls, branched fluorinated isoalkyls, thefluorinated alkyls and isoalkyls having from 1 to 20 carbon atoms, andoxaperfluorinated polyethers having from 4 to about 60 carbon atoms; xis 1 to about 250 and, more preferably, 2 to about 100; and y is 1 toabout 250 and, more preferably, 2 to about 100.

In addition to providing hydroxy-terminated FOX homo- and coprepolymers,the present invention provides a method of making the FOX homo- andcoprepolymers. Generally, the method of making the FOX homo- andcoprepolymers includes the steps of:

1) charging a reactor with a catalyst, an initiator and a solvent;

2) adding a solution of FOX monomer(s) in an appropriate organic solventat a temperature between −20° C. and +60° C.;

3) reacting the FOX monomer(s) with the catalyst/initiator solution;

4) quenching the reaction; and

5) separating the FOX prepolymer by precipitation in methanol.

The polymerization reaction can be a homopolymerization reaction or aco-polymerization reaction in which a mixture of two or more of theabove-mentioned oxetane monomers is added to the polymerization zone. Aparticularly useful co-polymerization is a block polymerization in whichthe comonomers are sequentially added in selected proportions to obtainblock copolymers of controlled block sizes and properties.

In accordance with the present invention, solution polymerization can beconducted at a solids concentration of about 5% to about 85% and, morepreferably, at a solids concentration of about 50 to about 60% solids.The polymerization reaction is conducted in the presence of a suitableinert solvent and, preferably, a halogenated C₁ to C₅ hydrocarbon.Examples of suitable solvents include, but are not limited to, methylenechloride, carbon tetrachloride, chloroform, trichloroethylene,chlorobenzene, ethyl bromide, dichloroethane, fluorinated solvents, etc.In a preferred embodiment, methylene chloride or a mixture of methylenechloride and Freon™ is employed. Other solvents, such as sulfur dioxide,hexanes, petroleum ether, toluene, dioxane and xylene, can also be used.

The FOX monomers readily polymerize in the presence of a Lewis acidcatalyst, i.e., a compounds capable of accepting a pair of electrons,and a polymerization initiator. Suitable Lewis acid catalysts include,but are not limited to, complexes of boron trifluoride, phosphoruspentafluoride, antimony pentafluoride, zinc chloride, aluminum bromide,and the like. In a preferred embodiment, the Lewis acid catalyst isboron trifluoride tetrahydrofuranate, i.e., a BF₃.THF complex. Thepolymerization initiator is preferably a polyhydroxy aliphatic compound.Examples of suitable polymerization initiators include, but are notlimited to, alkyl and isoalkyl polyols having from about 2 to about 5carbon atoms and from about 2 to about 4 hydroxyls. Such compoundsinclude, for instance, ethylene glycol, butane-1,4-diol, propyleneglycol, isobutane-1,3-diol, pentane-1,5-diol, pentaerythritol,trimethylolpropane, and the like. In a presently preferred embodiment,butane-1,4-diol is the polymerization initiator used.

The catalyst and initiator are preferably mixed for about 5 to about 10minutes in the solvent prior to the addition of the FOX monomers. Theratio of catalyst to initiator can range from about 1:1 to about 1:5mol/mol and, more preferably, from about 1:1 to about 1:2 mol/mol. Anexample of a preferred catalyst, initiator and solvent system isBF₃.THF, butane-1,4-diol and methylene chloride. The ratio of themonomer to the catalyst ranges from about 5:1 mol/mol to about 300:1mol/mol and, more preferably, from about 10:1 mol/mol to about 50:1mol/mol.

In a typical example, the catalyst and the initiator are mixed in asolvent prior to the addition of the FOX monomer(s). As oxetane monomerspossess relatively high strain energy and undergo exothermic,ring-opening polymerizations, the FOX monomer(s) is added slowly over aperiod of time to control the reaction temperature and to avoid run-awayreactions. The progress of the reaction is monitored by ¹H NMR and whengreater than about 95% of the FOX monomer is consumed, the reaction isquenched with water. The prepolymer is purified, for example, byprecipitation in methanol.

The molecular weight of the prepolymer can be controlled by varying themonomer/initiator ratio. Generally, lower monomer/initiator ratios favorthe formation of lower molecular weight prepolymers. The ratio ofmonomer to initiator can range from about 5:1 mol/mol to about 300:1mol/mol, more preferably, from about 10:1 mol/mol to about 100:1 mol/moland, more preferably, from about 5:1 mol/mol.

The reaction temperature can be varied from about −20° to about +60° C.In a preferred embodiment, the reaction temperature is about +5° C. Athigher temperatures, formation of monofunctional materials, mainly —CH₂Fterminated materials, is observed. Monofunctional materials can act aschain terminators, thereby limiting the molecular weight of the finalpolymer as well as increasing the polydispersity. This, in turn, canresult in polymers having poor mechanical and physical properties.

Cyclic oligomers are normally formed as by-products in the synthesis ofpolyether prepolymers. Such materials are nonfunctional and, thus,reduce the usefulness of the prepolymers. Moreover, these materials canleach out of the polymer matrix, thereby drastically affecting thesurface and mechanical properties of the polymer. Prepolymers preparedby homopolymerization of FOX monomers contain approximately 2-7% cyclictetramer.

However, the formation of cyclic oligomers can be controlled somewhat bythe choice of catalyst employed. For instance, the BF₃.etherate catalystresults in about 10% to 15% of monofunctional material and about 6% to7% cyclic tetramer by-product. In contrast, BF₃.THF, the preferredcatalyst used in the methods of the present invention, results in lessthan 7% of the cyclic tetramer byproduct and eliminates the formation ofthe monofunctional materials. In turn, this increases the functionalityof the prepolymer and leads to polymers having excellent mechanical,surface, and physical properties.

The polymerization of FOX monomers occurs by cationic ring-openingreaction, a possible mechanism for which is presented in FIG. 1.Polymerization is initiated by the proton donated by the initiator, andthe protonated oxetane ring undergoes propagation with other oxetanes togenerate the polymer chain. The growing polymer chain is then terminatedwith either an alcohol or water to give the hydroxy-terminated polyetherprepolymers of this invention. It should be noted that the prepolymersof this invention are mixtures of prepolymers resulting from bothalcohol and water terminations.

The prepolymers of this invention are amorphous, low-viscosity oils thatare easy to process. The inherent viscosity of the prepolymers arebetween 0.05 and 0.08 dL/g. The number of average molecular weights ofthe prepolymers, as determined by gel permeation chromatography, arebetween 1,000 and 30,000. The polydispersity, a measure of the spread or“Q” of the molecular distribution, is very low, i.e., on the order ofless than 5 and typically between 1.1-2.0. The prepolymers exhibitunimodal molecular weight distribution, and typically contain only about2-7% cyclic tetramer.

It should be noted that molecular weights reported in this invention areexpressed relative to well-characterized polystyrene standards. Theequivalent weight of the prepolymers was determined by ¹H NMR employingTFAA end group analysis and were between 2,500 and 9,000. The glasstransition temperature (T_(g)) of the prepolymers, as determined by DSCanalysis, was between −38° C. and −45° C.

The structural analysis of the homo- and coprepolymers of this inventionwas conducted with ¹H, ¹³C and ¹⁹F NMR spectroscopy. ¹H NMR analysisrevealed the presence of a trimethyleneoxide-based polyether backbone.¹H NMR analysis also indicated that when BF₃.etherate is used as thecatalyst, substantial amounts of mono-functional material with —CH₂F and—OCH₂CH₃ end-groups is formed. However, when BF₃.THF is used as thecatalyst, formation of mono-functional material is not observed. ¹H NMRwas also used to establish the ratio of the monomers in the coprepolymerand the identity of the end groups. ¹⁹F NMR analysis confirmed thepresence of fluoroalkyl side chains and the absence of materials with—CH₂F end groups and other impurities, such as Freon, HF and the BF₃catalyst.

The prepolymers of the present invention are oils that can be used aslubricants or as additives for a variety of applications. For example,these materials can be used as additives in cosmetics to impart waterrepellency and release characteristics. In addition, these materials canbe used as additives in engine oils to reduce engine wear and improveperformance. The principal application, however, is in the preparationof fluorinated polymers which, in turn, can be used for diverseapplications ranging from car wax to materials for medical and dentalapplications, such as prosthetics and catheter linings.

2. Hydroxy-Terminated FOX/THF Coprepolymers

In another embodiment, the present invention provides hydroxy-terminatedFOX/THF coprepolymers. It has been discovered that the fluorinatedoxetanes of this invention can be copolymerized with THF to provide aFOX/THF coprepolymer having very unique and unexpected characteristics.Such coprepolymers are a new class of fluorine containing,hydroxy-terminated, polyether prepolymers that, when cured withpolyisocyanates, provide tough polyurethane elastomers that arecharacterized by low glass transition temperatures and low surfaceenergies. Moreover, these elastomers can be incorporated into coatingsthat exhibit high abrasion resistance and a low coefficient of friction.Combinations of these properties make the polymers derived from thesefluorinated coprepolymers extremely attractive for a variety ofapplications including, but not limited to, anti-fouling (i.e., release)coatings; ice release coatings; corrosion resistant coatings, automotivetop coats (e.g., car wax), windshield wipers; belt strips; varioushousehold goods; seals and gaskets; encapsulants for electronic devices;oil and dirt resistance coatings; and numerous medical/dentalapplications.

Tetrahydrofuran (THF) is a five-membered cyclic ether that iscommercially available and is known to polymerize or copolymerize withcationic catalysts, but not with anionic catalysts. Attempts tocopolymerize THF with cyclic ethers and, in particular, oxetanes areunpredictable. Polymerization occurs, but the products are often notrandom copolymers. Due to the vast differences in ring-openingpolymerizability between THF and oxetanes, it is more likely that theproduct is a block copolymer, rather than a random copolymer. Poly(THF)(PTHF) is a semicrystalline polymer that melts at about 50° C., and whenemployed as the soft segment in urethane elastomers, is likely tocrystallize at low temperatures, thereby causing problems with physicalproperties, such as poor flexibility, incomplete or little recoveryafter elongation, poor modulus, and the like. In a block or nonrandomcopolymer, similar problems can occur since THF blocks can crystallizeand form semicrystalline polymers.

In the FOX/THF random coprepolymer of this invention, THF and oxetanesegments are more or less randomly spaced along the polymer backbone,thereby leading to products that are amorphous oils. The more or lessrandom nature of the FOX/THF coprepolymers of the present inventionprevents backbone tacticity or any other form of regularity that lendsitself to ordering and, in turn, crystallinity. Hydroxy-terminatedpolyether prepolymers that are low in crystallinity, preferablyamorphous, are particularly suitable as the soft segments for urethaneelastomers.

In this invention, the FOX monomers (either bis-substituted or a mixtureof bis- and mono-substituted FOX monomers) can be copolymerized withtetrahydrofuran to give FOX/THF coprepolymers. Copolymerization of FOXmonomers with THF not only reduces the cost of fluorinated prepolymersby using less of the relatively more expensive FOX monomers, but alsoprovides prepolymers with superior properties. The coprepolymers of thisinvention are random copolymers and are ideal as soft segments forurethane elastomers. Moreover, these FOX/THF coprepolymers are amorphousoils that are easy to process. Also, the use of THF as a coreactantallows the polymerization to be conducted in bulk and eliminates the useof ozone depleting solvents, such as Freons™.

In one embodiment, the FOX/THF coprepolymer comprises a mixture ofmonomeric units having the following general formulae:

In the above formula, n is independently selected and is 1 to 3; R_(f) ¹and R_(f) ² are independently selected from the group consisting oflinear perfluorinated alkyl groups having 1-20 carbons, branchedperfluorinated alkyl groups having 1-20 carbons and oxaperfluorinatedpolyethers having from about 4-60 carbons; x is 1 to about 250 and, morepreferably, 2 to about 100; and z is 1 to about 250 and, morepreferably, 1 to about 100. Typically, the molecular weight (M_(n)) ofthe FOX/THF coprepolymers ranges from about 2,000 to about 50,000 and,more preferably, from about 2,000 to about 15,000; and the T_(g) is lessthan about −200.

In another embodiment, the FOX/THF coprepolymers of the presentinvention comprise a mixture of monomeric units having the followinggeneral formulae:

In the above formula, each n is independently selected and is 1 to 3; Ris selected from the group consisting of methyl and ethyl; R_(f) ¹,R_(f) ² and R_(f) ³ are independently selected from the group consistingof linear perfluorinated alkyl groups having 1-20 carbons, branchedperfluorinated alkyl groups having 1-20 carbons and oxaperfluorinatedpolyethers having from about 4-60 carbons; x is 1 to about 250 and, morepreferably, 2 to about 100; y is about 1 to about 250 and, morepreferably, 2 to about 100; and z is 1 to about 250 and, morepreferably, 1 to about 100. Typically, the molecular weight (M_(n)) ofthe FOX/THF coprepolymers ranges from about 2,000 to about 50,000 and,more preferably, from about 2,000 to about 15,000; and the T_(g) is lessthan about −20° C.

Unexpectedly, the resulting coprepolymers of this invention are more orless random. The more or less random sequence of the coprepolymers,together with the presence of the asymmetric FOX segment, results in alow-viscosity oil that significantly facilitates processing and thecommercial application of the product. Moreover, the surface energy ofthe FOX/THF coprepolymers, as cured polymers, is lower than that ofpolytetrafluoroethylene (TEFLON™). This lower surface energy is thoughtto be due to the presence of the fluorine in the side chains of thepolymer, rather than in the backbone of the polymer. Even though theamount of fluorine in the FOX/THF coprepolymer has been reduced by theintroduction of the THF segments, it has thus far been determined thatwhen the FOX/THF copolymer contains up to about 65% THF, no significantreduction in surface energy is observed in polyurethane elastomers ascompared to the elastomers prepared from the mono-substituted FOXmonomers.

The random nature of the coprepolymer sequence is wholly unexpected andis achieved with the novel reaction conditions outlined below. The moreor less randomness results in an amorphous, low-viscosity oil. Thebenefits of a liquid prepolymer over a crystalline prepolymer include,for example, easier processing and mixing with reactants (e.g.,diisocyantes, crosslinkers, chain extenders, etc.).

As such, in another embodiment, the present invention provides asemi-batch method of making FOX/THF coprepolymers. Generally, the methodof making the FOX/THF coprepolymers of the present invention includesthe following steps:

1) premixing THF in an appropriate organic solvent, the THF and solventtemperature being between about −20° C. and about +60° C.;

2) adding a catalyst;

3) adding an initiator;

4) adding at a controlled rate a FOX monomer(s), the temperature of theFOX monomer(s) being between about −20° C. and about +60° C.;

5) quenching the reaction; and

6) separating the FOX/THF prepolymer by precipitation in methanol.

Importantly, when the copolymer ratio of FOX to THF ranges from about60:40 mol/mol to about 35:65 mol/mol, no organic solvent is required andthe prepolymer can be made by the addition of FOX to neat THF. Theabsence of solvent offers significant advantages to manufacturers withrespect to the environmental costs associated with the storage, handlingand disposal of hazardous materials, as well as the lower manufacturingcosts and enhanced public perception (i.e., a “green” product). Further,the presence of the hydrocarbon segment, i.e., the THF segment, improvessolubility of the FOX/THF coprepolymers in hydrocarbons.

Solution polymerization can be conducted at a solids concentrationranging from about 5% to about 85% and, more preferably, from about 50%to about 60% solids. The copolymerization is conducted either in aninert solvent, such as methylene chloride, Freon™ 113 or mixturesthereof, or in neat THF. Other solvents suitable for use in this processinclude, but are not limited to, carbon tetrachloride, chloroform,trichloroethylene, chlorobenzene, ethyl bromide, dichloroethane,fluorinated solvents, sulfur dioxide, hexanes, petroleum ether, toluene,trifluorotoluene, trifluorochlorotoluene, dioxane, xylene, etc. In apreferred embodiment, the solvent is methylene chloride or a mixture ofmethylene chloride and Freon™. The fact that FOX/THF copolymers can beprepared in the absence of a solvent is beneficial in the view offull-scale production, since environmental regulations highly restrictthe emission of solvents, especially halogenated solvents, into theatmosphere.

The catalyst and the initiator are similar to those used in the homo- orco-polymerization of FOX monomers. Suitable catalysts are Lewis acids,i.e., compounds capable of accepting a pair of electrons. Examples ofLewis acids include, but are not limited to, complexes of borontrifluoride, phosphorous pentafluoride, SnCl₄, antimony pentafluoride,etc. Suitable initiators include water and aliphatic alcohols containing2 to 5 carbons and 1 to 4 hydroxy groups. Suitable aliphatic alcoholsinclude, but are not limited to, trifluoroethanol, methanol,1,4-butanediol, trimethylolpropane, pentaerythritol, etc.

In a typical example, the catalyst and the initiator are mixed in asolvent prior to the addition of the monomer. THF is a five-memberedcyclic ether with low strain energy, and does not readily homopolymerizeunder the reaction conditions of temperature and monomer concentrationemployed. Thus, THF can be added in one shot to the reaction mixture. Onthe other hand, oxetane monomers possess relatively high strain energyand undergo exothermic, ring-opening polymerizations. Thus, the FOXmonomers are added slowly over a period of time to control the reactiontemperature and to avoid run-away reactions. The progress of thereaction is monitored by ¹H NMR and when greater than 95% of FOX monomeris consumed, the reaction is quenched with water. The prepolymer ispurified, for example, by precipitation in methanol.

As previously described, the molecular weight of the FOX/THFcoprepolymers can be controlled by varying the monomer/initiator ratio.Generally, lower monomer/initiator ratios favor the formation of lowermolecular weight coprepolymers. The ratio of monomer to initiator canrange from about 5:1 mol/mol to 300:1 mol/mol. In a presently preferredembodiment, the ratio of monomer to initiator employed is about 5:1mol/mol to 100:1 mol/mol. The temperature can range from about −20° C.to +60° C., with the presently preferred temperature being about +5° C.At higher temperatures, formation of monofunctional materials, mainly—CH₂F terminated materials, is observed. If the reaction is carried outat about +5° C., the formation of —CH₂F terminal groups, which areunreactive and reduce the functionality of the prepolymer (by formationof the monofunctional product) and lead to polyurethanes with poormechanical properties, is eliminated.

In contrast to the FOX homo- and co-prepolymers, the formation of largeamounts of cyclic oligomers is not observed in the copolymerization ofFOX monomers with greater than 10 mole % THF. It is postulated that theincorporation of THF into the growing polymer chain changes the numberof carbon atoms between oxygen atoms in the polymer chain and does notallow the chain to bite back and form a thermodynamically stable,16-membered cyclic ether. This result is especially important in thedevelopment of coatings, where discharge of any chemicals from candidatecoatings is not acceptable.

The FOX/THF coprepolymers of this invention are amorphous, low-viscosityoils that are easy to process. FOX/THF coprepolymers are slightly moreviscous than FOX homoprepolymers. ¹H NMR analysis of FOX/THFcoprepolymers indicates that both monomers are incorporated into thecoprepolymer, and that the THF segment is primarily present in themiddle of two FOX segments, and not as an end group.

The ratio of the two monomers in the coprepolymer is established bycomparing the area under the peaks corresponding to THF (about 1.6 ppm)and the FOX monomers segments. ¹H NMR analysis also indicates thatFOX/THF copolymers are not contaminated with monofunctional materials(—CH₂F terminated) or other impurities. The presence of multiple peaksin the quartenary carbon region of ¹³C NMR, corresponding to the carbonbearing the fluoroalkyl side chain, reveals that the above prepolymersare nearly random copolymers with little, if any, block structure. ¹⁹FNMR analysis confirms the presence of the fluoroalkyl side chain and theabsence of —CH₂F end groups, HF and BF₃ catalyst. It is important tonote that these materials do not contain THF block sequences long enoughto crystallize, which could lead to materials with poor flexibility.

The number of average molecular weights of FOX/THF coprepolymers, asdetermined by GPC, were between 10,000 and 14,000, whereas M_(W)/Mn werebetween 1.1 and 2.5. The coprepolymers exhibit unimodal molecular weightdistributions, and are typically free of cyclic oligomers. It should benoted that the formation of a random copolymer between bis-substitutedFOX monomers and THF monomers is unexpected.

The coprepolymers described above are oils that can be used aslubricants or as additives for a variety of applications. For example,the coprepolymers can be used as additives to improve the performance ofcommercial engine oils or as lubricants for industrial equipment. Themajor use of FOX/THF coprepolymers, however, is in the development offluorinated polyether urethane elastomers as described herein.

D. POLYMERS

The hydroxy-terminated prepolymers of this invention can be used for thesynthesis of a variety of polymers, such as polyurethanes, polyesters,polycarbonates, polyacrylates, etc. In addition, the FOX prepolymers ofthis invention can be used to synthesize novel fluorinated elastomers,thermosets and thermoplastics.

1. Polyurethanes from FOX Homo-/Coprepolymers

The preparation of fluorinated polyurethane elastomers begins with theFOX prepolymers of this invention. As previously described, theseprepolymers are amorphous, low-viscosity oils that are easy to process.Moreover, these materials are difunctional and possess terminal primaryhydroxy groups that react readily with isocyanates to form highmolecular weight polyurethane elastomers. Typically, the prepolymer isreacted with an equivalent amount of a polyisocyanate in the presence ofa catalyst and a crosslinking agent to form a three-dimensional, polymernetwork. The process involves mixing the components, casting them in amold, degassing and curing the mixture at an elevated temperature.Alternatively, the FOX prepolymer is reacted with excess diisocyanateand the resulting isocyanate-capped prepolymer is reacted with acrosslinking agent to form a thermoset. If desired, theisocyanate-capped prepolymer can be reacted with a low molecular weightdiol or diamine, i.e., a chain extender, to form a linear, thermoplasticpolyurethane elastomer.

In one embodiment, the fluorine-containing thermoplastic polyurethaneelastomer of this invention comprises a mixture of monomeric unitshaving the following general formulae:

In the above formula, n is independently selected and is 1 to 3; R_(f) ¹and R_(f) ² are independently selected from the group consisting oflinear and branched perfluorinated alkyls having 1-20 carbon atoms, andoxaperfluorinated polyethers having from about 4-20 carbon atoms; R¹ isa divalent hydrocarbyl radical; x is 1 to about 250 and, morepreferably, 2 to about 100; and w is 1 to about 50 and, more preferably,1 to about 5. It is noted that R_(f) ¹ and R_(f) ² are selected suchthat they are different. Examples of suitable divalent hydrocarbylradicals include, but are not limited to, the following structures:

In another embodiment, the fluorine-containing thermoplasticpolyurethane elastomer of this invention comprises a mixture ofmonomeric units having the following general formulae:

In the above formula, n is independently selected and is 1 to 3; R isselected from the group consisting of methyl and ethyl; R_(f) ¹, R_(f) ²and R_(f) ³ are independently selected from the group consisting oflinear and branched perfluorinated alkyls having 1-20 carbon atoms, andoxaperfluorinated polyethers having from about 4-20 carbon atoms; R¹ isa divalent hydrocarbyl radical; x is 1 to about 250 and, morepreferably, 2 to about 100; y is 1 to about 250 and, more preferably, 2to about 100; and w is 1 to about 50 and, more preferably, 1 to about 5.

The resulting polyurethanes are tack-free, opaque and generallyinsoluble in organic solvents and have glass transition temperaturesbetween about −40° C. and about −47° C. Contact angle measurements ofbetween 110° and 145° with distilled water and surface energymeasurements of 13.8-15.2 ergs/cm² indicate that the surface wettabilityand nonadhesive characteristics of the elastomers of this invention aregreater than those measured for TEFLON™ (110° contact angle and 18.5ergs/cm² surface energy). It has generally been found that as the sizeof the side chain on the FOX polymers increases, hydrophobicityincreases as well.

The polyurethanes of this invention exhibit the following novel set ofcharacteristics:

1) Elastomeric properties;

2) More hydrophobic and nonstick than TEFLON™;

3) Processable into thin coatings or bulk articles;

4) Flexible down to about −50° C.;

5) Bondable to a variety of substrates; and

6) Useful ambient temperature range from about −50° C. to about 240° C.

The glass transition temperature (T_(g)) is the temperature at which thepolymer is transformed from a brittle glass to a flexible elastomer.Thus, it dictates the lower use temperature of the elastomer. The glasstransition temperatures of non-plasticized FOX polyurethanes, asmeasured with a differential scanning calorimeter (DSC), are between−40° C. and −47° C. Normally, a plasticizer is used to impartflexibility and to lower the glass transition temperature of thepolymers. If desired, fluorinated plasticizers, such as Fomblin, Alfunoxand Kel-F oils, can be used to improve the low-temperature flexibilityof the FOX polyurethane elastomers of the present invention.

The contact angle is the obtuse angle of a water droplet on the polymersurface and reflects the wettability of the polymer surface. A waterdroplet does not spread on a hydrophobic surface and will exhibit a highcontact angle, indicating non-wetting characteristics of the polymersurface. The static contact angle of FOX polyurethanes with doublydistilled water were measured with a Goniometer, and were found to bebetween 110° and 145°. In sharp contrast, TEFLON™ exhibits a contactangle of 110°. Surface energy is also an important measure ofwettability of the polymer surface and defines critical properties, suchas hydrophobicity and adhesive characteristics. Materials with lowsurface energies are difficult to wet and, thus, exhibit excellentrelease characteristics. TEFLON™, for example, exhibits a surface energyof 18.5 ergs/cm², and is widely used in the preparation of nonstickcooking utensils. Surface energies of common polymers are listed inTable 2. The surface energy values of the polymers of the presentinvention are considerably lower than that of TEFLON™ and othercommercial polymers, indicating that FOX polyurethanes have superiorrelease characteristics to TEFLON™. This makes the cured elastomer ofthe present invention more suited than TEFLON™ for those applicationswhere lower wettability and enhanced release characteristics are desiredin a coating material.

TABLE 2 SURFACE ENERGIES OF COMMERCIAL POLYMERS SURFACE Material(ergs/cm²) TEFLON ™ 18.5 Polydimethylsiloxanes 24 Polyethylene 31Polytrichlorofluoroethylene 31 Polystyrene 33-35Poly(methylmethacrylate) 33-34 Nylon 66 46

In another embodiment, the present invention provides methods for makingthe polyurethane elastomers of the present invention. In one embodiment,the method includes the steps of:

1) premixing a FOX prepolymer with a polyisocyanate at a temperaturebetween about 25° C. and about 100° C.;

2) adding a catalyst;

3) adding from about 0% to about 15% wt/wt of a crosslinking agent;

4) mixing the components;

5) casting the components into a mold;

6) degassing the cast compound; and

7) curing the compound mixture at a temperature of between about 17° C.and about 150° C.

Normally, molar equivalent amounts of the FOX prepolymer, polyisocyanateand crosslinking agent are used. However, where the FOX prepolymer isadded to an excess of polyisocyanate, an isocyanate-capped prepolymer isproduced that can be further reacted with a crosslinking agent toproduce a thermoset polyurethane elastomer. Alternatively, theisocyanate-capped prepolymer can be reacted with a low molecular weightchain extender, such as a diol or diamine, to prepare linearthermoplastic polyurethane elastomers.

Polyisocyanates suitable for use in the synthesis of the FOXpolyurethanes of the present invention include, but are not limited to,hexamethylene diisocyanate (HDI), isopherone diisocyanate (IPDI),methylene diphenylisocyanate (MDI), saturated MDI (Des-W), polymericMDI, which are available from Dow Chemical Co. under the trademarkISONATE, a line of low-functionality isocyanates, toulene diisocyanate(TDI), polymeric HDI, which are available from Mobay Corporation, aBayer Company, under the trademarks DESMODUR N-100, a solvent-free,aliphatic polyisocyanate resin basin based on hexamethylenediisocyanate, and DESMODUR N-3200, an aliphatic polyisocyanate resinbased on hexamethylene diisocyanate, cyclohexylene-1,4-diisocyanate, and2,2,4-trimethylhexmethylene diisocyanate. The NCO:OH ratio can rangefrom about 1.1 to about 0.9 and, more preferably, NCO:OH ratio is about1.02.

The crosslinking agents normally used are low molecular weight polyolsor polyamines. Examples of suitable crosslinking agents include, but arenot limited to, trimethylolpropane, pentaerythritol, ISONOL® 93,trimethylolethane, triethanolamine, Jeffamines, 1,4-butanediamine,xylene diamine, diethylenetriamine, methylene dianiline, diethanolamine,etc. In preferred embodiments, trimethylolpropane, ISONOL® 93, methylenedianiline and Jeffamines are the crosslinking agents employed. Themechanical properties of the elastomers can be altered by varying theamount of crosslinking agent. Generally, increasing the amount ofcrosslinking agent in a polyurethane formulation leads to materials withhigher modulus and improved chemical and abrasion resistance. The amountof crosslinking agent can be varied from about 0 to about 15% by weightand, more preferably, from about 1.5% to about 5% by weight.

Catalysts suitable for use in the present invention include, but are notlimited to, triethylamine, triethylene diamine, triphenyl bismuth,chromium acetylacetonate, lead octonate, ferric acetylacetonate, tinoctanoate, dibutyltin dilaurate, and the like. In a preferredembodiment, the catalyst is dibutyltin dilaurate. It should be notedthat the catalyst is added primarily to increase the rate of thereaction and, if desired, the reaction can be conducted in the absenceof the catalyst. The catalyst concentration can range from about 0.001to about 1% by wt. and, more preferably, from about 0.1% and 0.2% by wt.

Bulk materials are prepared by casting the above formulation in a mold,degassing the mixture, and then curing the mixture at a temperatureranging from about 20° C. to about 150° C. for about 3 to about 36hours. In a presently preferred embodiment, the cure temperature isabout 65° C. It is noted that the above formulation can be cured at roomtemperature by increasing the amount of catalyst to about 0.5%. The cureis also dependent on the thickness of the sample and the type ofcrosslinking agent employed. Thin samples cure within about 3 hours at65° C., whereas ⅛ inch thick sample can take between about 8 to about 16hours to cure. A thin-film is prepared by diluting the above formulationwith THF, spreading the mixture over the substrate with, for example, aDoctor's blade, and then curing the coated substrate in an oven at 65°C. Alternatively, the substrate can be dip coated or spray coated andcured in an oven at 65° C. In addition, amine-based crosslinking agentspromote faster cures than polyols.

The mechanical properties of the polyurethanes prepared from FOXprepolymers indicate that they are true elastomers (i.e., >100%recoverable elongation). Moreover, the FOX polyurethanes of the presentinvention exhibit surprisingly good adhesion to a variety of substratesincluding, but not limited to, stainless steel, aluminum, graphite, EPDMrubber, glass and wood. In a typical process, the substrate is coatedwith the polyurethane formulation, placed in an oven, and cured. It isnoted that no special treatment or primer is required to bondfluorinated polyurethane to the substrate. The good bondingcharacteristics of the FOX polyurethanes of the present invention areattributed to the presence of the polar urethane groups in the polymerbackbone that, in contrast to fluoroalkyl groups, orient towards thehigh energy surface. A well-adhering coating should, therefore, containchemical groups that will contribute to enhance the polarity of thecoating and bring it into the range of the substrate. A systemcontaining both dipole-dipole and hydrogen-bond contributions ispreferred over a system containing only one such contribution because ofits broader compatibility. During application, the system must besufficiently fluid in order to encourage rapid spreading, uniformcoating and good wetting. Since TEFLON™ has the fluorines symmetricallybonded to the polymer backbone, there is no dipole or hydrogen bondingwhich will allow the polymer to bond to a substrate surface.Consequently, a TEFLON™ coating will not exhibit good adhesion or peelstrength with its underlying substrate.

The thermal stability of the FOX polyurethanes is determined bythermogravimetric analysis (TGA). The FOX polyurethanes of the presentinvention exhibit 0% wt. loss in air to 260° C., and an onset of majorthermal degradation in air at 275° C. As such, the FOX polyurethanesshould not be exposed to temperatures in excess of 250° C.

The above results indicate that the polyurethanes prepared from the FOXprepolymers of the present invention are more hydrophobic and nonstickthan TEFLON™. In sharp contrast to TEFLON™, FOX polyurethanes are toughelastomers that can be processed into either thin coatings or bulkarticles. Moreover, these materials are flexible at low temperatures andcan be used at temperatures as low as −50° C. Also, these materials canbe bonded to a variety of substrates, and can be used at temperaturesranging from about −50° C. to about 250° C. As such, this inventionprovides novel materials that can be bonded strongly to a variety ofsubstrates and, at the same time, provide a surface that is morehydrophobic and nonstick than TEFLON™. Materials having this combinationof properties are extremely useful as processable, low-surface-energyelastomers.

2. Polyurethanes from FOX/THF Coprepolymers

The FOX/THF coprepolymers of the present invention can also be used toproduce polyurethane elastomers having useful properties. Polyurethanesprepared from FOX/THF coprepolymers exhibit better adhesion, higherabrasion resistance and superior mechanical properties than thosederived from FOX homo- or coprepolymers. Moreover, the key properties ofFOX polyurethanes are not affected by incorporation of THF into thepolymer structure. That is, polyurethanes prepared from FOX/THFcoprepolymers still exhibit low glass transition temperatures, lowcoefficients of friction, and low-surface-energy properties that aresimilar to those of polyurethanes derived from FOX homo- orcoprepolymers.

As such, in one embodiment, the present invention a fluorinatedthermoset polyurethane elastomer having random FOX/THF segments andcomprising a mixture of monomeric units having the general formulae:

In the above formula, n is independently selected and is 1 to 3; R_(f) ¹and R_(f) ² are independently selected from the group consisting oflinear and branched perfluorinated alkyls having 1-20 carbon atoms, andoxaperfluorinated polyethers having from about 4-20 carbon atoms; R¹ isa divalent hydrocarbyl radical; x is 1 to about 250 and, morepreferably, 2 to about 100; z is 1 to about 250 and, more preferably, 1to about 100; and w is 1 to about 50 and, more preferably, 1 to about 5.

In another embodiment, the present invention provides a fluorinatedthermoset polyurethane elastomer comprising a mixture of monomeric unitshaving the general formulae:

In the above formula, n is independently selected and is 1 to 3; R isselected from the group consisting of methyl and ethyl; R_(f) ¹, R_(f) ²and R_(f) ³ are independently selected from the group consisting oflinear and branched perfluorinated alkyls having 1-20 carbon atoms, andoxaperfluorinated polyethers having from about 4-20 carbon atoms; R¹ isa divalent hydrocarbyl radical; x is 1 to about 250 and, morepreferably, 2 to about 100; y is 1 to about 250 and, more preferably, 2to about 100; z is 1 to about 250 and, more preferably, 1 to about 100;and w is 1 to about 50 and, more preferably, 1 to about 5.

The FOX/THF coprepolymers described in this invention are difunctionaland have terminal hydroxy groups. The hydroxy groups are primary hydroxygroups and, thus, they readily react with isocyanates to form highmolecular weight polyurethane elastomers. In a typical reaction, thecoprepolymer is reacted with an equivalent amount of polyisocyanate inthe presence of a catalyst and a crosslinking agent to form athree-dimensional polymer network. If the functionality of thepolyisocyanate is 2, then a crosslinking agent is needed to form acrosslinked network. However, if the functionality of the polyisocyanateis greater than 2, then no crosslinking agent is required. In someinstances, additional crosslinking agent is added to improve thechemical and abrasion resistance of the polymer. The crosslinking agentnormally used is a low molecular weight polyol or polyamine.

Polyisocyanates suitable for use in the synthesis of the FOXpolyurethanes of the present invention include, but are not limited to,hexamethylene diisocyanate (HDI), isopherone diisocyanate (IPDI),methylene diphenylisocyanate (MDI), saturated MDI (Des-W), polymericMDI, which are available from Dow Chemical Co. under the trademarkISONATE, a line of low-functionality isocyanates, toulene diisocyanate(TDI), polymeric HDI, which are available from Mobay Corporation, aBayer Company, under the trademarks DESMODUR N-100, a solvent-free,aliphatic polyisocyanate resin basin based on hexamethylenediisocyanate, and DESMODUR N-3200, an aliphatic polyisocyanate resinbased on hexamethylene diisocyanate, cyclohexylene-1,4-diisocyanate, and2,2,4-trimethylhexmethylene diisocyanate. The NCO:OH ratio can rangefrom about 1.1 to about 0.9 and, more preferably, the NCO:OH ratio isabout 1.02.

The crosslinking agents normally used are low molecular weight polyolsor polyamines. Examples of suitable crosslinking agents include, but arenot limited to, trimethylolpropane, pentaerythritol, ISONOL® 93,trimethylolethane, triethanolamine, Jeffamines, 1,4-butanediamine,xylene diamine, diethylenetriamine, methylene dianiline, diethanolamine,etc. In preferred embodiments, trimethylolpropane, ISONOL® 93, methylenedianiline and Jeffamines are the crosslinking agents employed. Themechanical properties of the elastomers can be altered by varying theamount of crosslinking agent. Generally, increasing the amount ofcrosslinking agent in a polyurethane formulation leads to materials withhigher modulus and improved chemical and abrasion resistance. The amountof crosslinking agent can be varied from about 0 to about 15% by weightand, more preferably, from about 1.5% to about 5% by weight.

Catalysts suitable for use in the present invention include, but are notlimited to, triethylamine, triethylene diamine, triphenyl bismuth,chromium acetylacetonate, lead octonate, ferric acetylacetonate, tinoctanoate, dibutyltin dilaurate and the like. In a preferred embodiment,the catalyst is dibutyltin dilaurate. It should be noted that thecatalyst is added primarily to increase the rate of the reaction and, ifdesired, the reaction can be conducted in the absence of the catalyst.The catalyst concentration can range from about 0.001 to about 1% by wt.and, more preferably, from about 0.1% and 0.2% by wt.

As with the polyurethanes prepared from the FOX prepolymers, bulkmaterials are prepared by casting the above formulation in a mold,degassing the mixture, and then curing the mixture at a temperatureranging from about 20° C. to about 150° C. for about 3 to about 36hours. In a presently preferred embodiment, the cure temperature isabout 65° C. It is noted that the above formulation can be cured at roomtemperature by increasing the amount of catalyst to about 0.5%. The cureis also dependent on the thickness of the sample and the type ofcrosslinking agent employed. Thin samples cure within about 3 hours at65° C., whereas ⅛ inch thick sample can take between about 8 to about 16hours to cure. A thin-film is prepared by diluting the above formulationwith THF, spreading the mixture over the substrate with, for example, aDoctor's blade, and then curing the coated substrate in an oven at 65°C. Alternatively, the substrate can be dip coated or spray coated andcured in an oven at 65° C. In addition, amine-based crosslinking agentspromote faster cures than polyols.

In general, polyurethanes prepared from FOX/THF coprepolymers aretack-free, opaque elastomers. They exhibit glass transition temperaturesof less than about −20° C., and typically have static contact angleswith water between about 108° and about 126°. These materials areinsoluble in common organic solvents, such as methanol, toluene,hexanes, carbon tetrachloride, methyl ethylketone and kerosene, butswell in THF and Freon™ 113. Such materials exhibit good to excellentadhesion to a variety of substrates, such as stainless steel (SS 304),graphite, EPDM rubber, aluminum and glass. Typically, the substrate iscleaned with water and acetone and then dried in an oven prior to use.Bonding is achieved by curing the mixture of prepolymer, crosslinkingagent, polyisocyanate and catalyst directly on the substrate.

The studies carried out with respect to these polyurethanes indicatethat the copolymerization of FOX monomers with THF not only reduces thecost of manufacturing fluorinated prepolymers, but also providesmaterial with superior properties. Moreover, FOX/THF polyurethanesexhibit better adhesion and superior mechanical properties than FOXpolyurethanes, while retaining the key properties of FOX polyurethanes,i.e., low glass transition temperature, high adhesion, processibility,high hydrophobicity, low coefficient of friction, low surface energy,etc.

As a result of their unique combination of properties, polyurethanesprepared from FOX/THF coprepolymers are useful as fouling releasecoatings; as abrasion resistant, low friction coatings for glass-runwindow channels, belts and windshield wipers; as bushing, gaskets, andengine mounts; as encapsulants for electronic devices; as binders forpropellants and flares; as artificial joints; as dental materials; andas coatings for automotive, marine and industrial applications. Thepreferred applications are fouling release coatings, coatings for windowchannels, and binders for propellants and flares.

The invention will be described in greater detail by way of specificexamples. The following examples are offered for illustrative purposes,and are not intended to limit the invention in any manner. Those ofskill in the art will readily recognize a variety of noncriticalparameters which can be changed or modified to yield essentially thesame results.

EXAMPLES

A. Experimental Section

NMR analysis was performed on a Bruker MSL-300 spectrometer at 300 MHzin deutrochloroform solution with proton and carbon shifts in ppmrelative to tetramethylsilane and fluorine shifts relative tofluorotrichloromethane. IR analysis by diffuse reflectance was performedon a Nicholet SX-5 spectrometer on KBr. Thermal analysis was performedon a Dupont DSC 9100 Analyzer.

B. Monomers

Example I

This example relates to the preparation and properties of3,3-bis-(2,2,2-trifluoroethoxymethyl)oxetane (B6-FOX) using twodifferent procedures.

i. Procedure A

Sodium hydride (50% dispersion in mineral oil, 18.4 g, 0.383 mol) waswashed with hexanes (2×) and was suspended in DMF (200 mL). Thentrifluoroethanol (38.3 g, 0.383 mol) was added dropwise over 45 minwhile hydrogen gas was evolved. The mixture was stirred for 30 min and asolution of 3,3-bis-(hydroxymethyl)oxetane di-p-toluenesulfonate (30.0g, 0.073 mol) in DMF (50 mL) was added. The mixture was heated to 75° C.for 64 h when ¹H NMR analysis of an aliquot showed that the startingsulfonate had been consumed. The mixture was poured into water andextracted with methylene chloride (2×). The combined organic extractswere washed with brine, 2% aqueous HCl, water, dried (MgSO₄), andevaporated to give 17.5 g (100%) of3,3-bis-(2,2,2-trifluoroethoxymethyl)oxetane as an oil containing DMF(<1%). The oil was purified by bulb-to-bulb distillation at 42-48° C.(0.1 mm) to give 15.6 g (79%) of analytically pure B6-FOX, colorlessoil: IR (KBr) 2960-2880, 1360-1080, 995, 840 cm⁻¹; ¹H NMR δ3.87 (s 4H),3.87 (q, J=8.8 Hz, 4H), 4.46 (s, 4 H); ¹³C NMR δ43.69, 68.62 (q, J=35Hz), 73.15, 75.59, 123.87 (q, J=275 Hz); ¹⁹F NMR δ−74.6(s). Anal. Calcd,for C₉H₁₂F₆O₃: C, 38.31; H, 4.29; F, 40.40. Found: C, 38.30; H, 4.30; F,40.19.

ii Procedure B

A 2 L round-bottom flask fitted with a mechanical stirrer, condenser anda thermometer was charged with 3,3-bis-(bromomethyl)oxetane (300 g, 1.2mol), trifluoroethanol (284 g, 2.8 mol), tetrabutylammonium bromide(39.9 g, 0.12 mol) and water (265 mL). The mixture was heated to 85° C.and a 50% aqueous potassium hydroxide solution (672 g, 5.1 mol) wasadded via an addition funnel over a period of 3 h. The progress of thereaction was monitored by GLC and when greater than 99% of3,3-bis-(bromomethyl)oxetane was consumed, the reaction mixture wascooled to room temperature and diluted with water (500 mL). The organicphase was separated and washed with 2% aqueous potassium hydroxidesolution (500 mL) and water (500 mL). The crude product was thendistilled under reduced pressure (bp=103° C./5 mm/Hg) to give 278 g(80%) of greater than 99% pure (GLC)3,3-bis-(2,2,2-trifluoroethoxymethyl)oxetane, a colorless oil. Spectralanalysis revealed that the product prepared by this process wasidentical with B6-FOX monomer prepared by Procedure A.

Example II

This example relates to the preparation and properties of3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-methyloxetane(B14-FOX).

A 12 L, round-bottom flask fitted with a mechanical stirrer and a refluxcondenser was charged with 3,3-bis-(bromomethyloxetane) (678 g, 2.8moles), 2,2,3,3,4,4,4-heptafluorobutane-1-ol (1165 g, 5.82 moles),tetrabutylammonium bromid (55.4 g, 0.17 moles), and water (1200 mL). Themixture was heated to 85° C. and a solution of 50% aq. sodium hydroxide(640 g, 8.0 moles) was slowly added over a period of 4 h. The resultingmixture was then heated at about 100° C. for 16 h, at which point GLCanalysis revealed that greater than 95% of the starting oxetane wasconsumed. The mixture was cooled to room temperature and the organiclayer was separated. The organic layer was then washed with water(2×1000 mL), dried (MgSO₄), filtered and fractionally distilled underreduced pressure. The first fraction, boiling at 27° C./2 mm/Hg,consisted of unreacted heptafluorobutanol and was recycled. The secondfraction boiling at 110° C./1 mm/Hg, was the desired product, i.e.,B14-FOX (776 g, 83%). The product was greater than 99% pure asdetermined by GLC area % analysis, ¹H NMR and ¹³C NMR. ¹H NMR δ3.86 (s,4 H), 3.93 (t, J=23.2 Hz, 4 H), 4.44 (s, 4 H); ¹³C NMR δ43.84, 68.03,73.51, 77.61, 115.39, 115.84, 119.6; ¹⁹F NMR δ−81.61, −121.0, −128.2.

A sample of this material was purified by column chromatography toprovide pure poly(B14-FOX) glycol. The crude mixture (10 g) ofpoly(B14-FOX) glycol and clyclic oligomers was filtered through a shortsilica gel plug using hexane and ethyl acetate as eluents. The desiredpoly(B14-FOX) glycol was present in the ethyl acetate fraction and wasisolated in 42% yield by evaporating the solvent under reduced pressure.The product, a white wax, was found by GPC analysis to contain <0.5%cyclic material: GPC: M_(W)=9,047, PD=1.34; ¹H NMR (CDCl₃/F¹¹³/TFAA):δ3.39 (s, 4H), 3.59 (s, 4H), 3.87 (t, 13.5 Hz, 4H), and 4.40 (s,—CH₂OCOCF₃); ¹³C NMR: δ46.4, 68.5 (t), 70.1 and 72.1 (signals fromcarbon bearing fluorines are not included).

Example III

This example relates to the preparation and properties of3,3-bis-(2,2,3,3,4,4,5,5,6,6,7,7,7-pentadecafluorooctyloxymethyl)oxetane(B30-FOX).

A mixture of 3,3-bis-(chloromethyl)oxetane (3.0 g, 19.4 mmol),pentadecafluorooctan-1-ol (16 g, 40 mmol), tetrabutylammonium bromide(13.2 g, 40 mmol), water (35 mL), and 50% aq. sodium hydroxide (3.5 g,44 mmol) was heated at 100° C. for 48 h. The reaction mixture wasdiluted with Freon™ 113 (10 mL) and the organic phase was separated. Theorganic phase was then washed with water, dried (MgSO₄), filtered andstripped of solvent under reduced pressure to give 16.1 g of the crudeproduce. Kugelrohr distillation of the crude product under reducedpressure (120-125/0.2 mm/Hg) provided 13.8 g (82%) of B30-FOX, an oil;¹H NMR δ3.87 (s, 4 H), 3.93 (t, J=23.8 Hz, 4 H), 4.44 (s, 4 H).

Example IV

This example relates to the preparation and properties of3,3-bis-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxymethyl)oxetane(B26-FOX).

A mixture of 3,3-bis-(iodomethyl)oxetane (4.3 g, 12.7 mmol),3,3,4,4,5,5,7,7,8,8,8-tridecafluorooctan-1-ol (9.1 g, 25 mmol),tetrabutylammonium bromide (0.54 g, 1.7 mmol) water (7.5 mL) and 50%sodium hydroxide (4.9 g, 61.2 mmol) was heated at 100° C. for 16 h. Thereaction mixture was diluted with a 1:1 mixture of Freon™ 113 andmethylene chloride and the organic phase was separated and washed withwater. The organic phase was then dried, filtered and stripped ofsolvent under reduced pressure to give 11 g of a yellowish brown oil.This oil was then distilled under reduced pressure as follows: fraction#1 (2.1 g), distilling at 85° C./0.8 mm/Hg, was unreacted alcohol;fraction #2, distilling at 140° C./0.5 mm/Hg, was the desired product,i.e., B26-FOX (6.5 g, 76%), an oil: ¹H NMR (CDCl₃): δ2.85 (m, 4 H), 3.55(m, 4 H), 3.80 (s, 4H), 4.40 (s, 4 H).

Example V

This example illustrates the preparation and properties of mixed3,3-bis-substituted oxetane monomers.

A 12 L, round-bottom flask fitted with a mechanical stirrer and a refluxcondenser was charged with 3,3-bis-(bromomethyloxetane) (683.2 g, 2.8moles), 2,2,3,3,4,4,4-heptafluorobutan-1-ol (580 g, 2.9 moles),trifluoroethanol (290 g, 2.9 moles), tetrabutylammonium bromide (55 g,0.17 moles) and 1.2 L of water. The mixture was heated to 85° C. and asolution of 50% aq. sodium hydroxide (320 g, 4 moles) was slowly addedover a period of 4 h (6 moles). The resulting mixture was then heated atabout 100° C. for 16 h, and then cooled to room temperature when theorganic layer was separated. The organic phase was then washed withwater (2×1000 mL), dried (MgSO₄), filtered and distilled under reducedpressure. Low boiling fractions were unreacted fluoroalcohols, while theremaining higher boiling fraction consisting of a mixture of3,3-bis-substituted oxetanes: B6-FOX, B14-FOX and3-(2,2,2-trifluoroethoxymethyl),3-(2,2,3,3,4,4-heptafluorobutoxymethyl)oxetane(M6-14-FOX)).

C. Pre-Polymers

The first two examples illustrate that homopolymerization ofbis-substituted oxetane monomers provide polyether glycols that arecrystalline with melting points greater than 20° C. It should be notedthat polyether glycols produced by this process are contaminated withsignificant amounts of cyclic materials. Since cyclic materials canreduce the crystallinity of the polyether glycol via plasticization,complete removal of cyclic material is warranted prior to melting pointdeterminations. Removal of cyclic materials can be achieved bychromatography.

1. Crystalline Polymers

Example I

This example illustrates the preparation and properties ofpoly[3,3-bis-(2,2,2-trifluoroethoxymethyl)oxetane] (poly(B6-FOX)glycol).

A 5 L round-bottom flask fitted with a mechanical stirrer, thermometerand an additional funnel was charged with a solution of trifluoroethanol(5.8 g, 0.058 mol) and boron trifluoride etherate (11.4 g, 0.81 mol) inmethylene chloride (900 mL). The mixture was stirred at ambienttemperature for 15 min and a solution of3,3-bis-(2,2,2-trifluoroethoxymethyl)oxetane (1146 g, 4.1 mmol) inmethylene chloride (485 mL) was added over a period of about 2.5 hours.The resulting mixture was then stirred at ambient temperature for 16 hat which time ¹H NMR analysis of an aliquot indicated that the startingoxetane had been consumed. The reaction was quenched with water and theorganic layer was washed with brine and 2% aquesous HCl. Evaporation ofthe solvent under reduced pressure afforded 1053 g (91%) ofpoly[3,3-bis-(2,2,2-trifluoroethoxymethyl)]oxetane, a white waxy solid:DSC: mp 71.7° C. (δH=26.35 Joules/g), decomposition >210° C.; GPC (THF):M_(W)=27,000, polydisperity index (PDI)=2.2; ¹H NMR 1.60 (m), 2.46 (s),3.36 (s, 4 H), 3.58 (s, 4 H), 3.79 (q, 4 H); ¹³C NMR 45.49,68.25 (q,J=33 Hz), 69.20, 70.97, 123.81 (q, J=280 Hz).

Example II

This example illustrates the preparation and properties ofpoly[3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane](Poly(B14-FOX) glycol).

In a manner similar to that described above, a solution of3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane (252 g, 523 mmol)in Freon™ 113 (75 mL) was added to a mixture of boron trifluorideetherate (1 g, 7.0 mmol) and trifluoroethanol (0.5 g, 5.0 mmol) inmethylene chloride (175 mL) at ambient temperature. The resultingmixture was stirred at ambient for 46 hours, at which time ¹H NMRanalysis revealed that greater than 95% of starting oxetane monomer wasconsumed. The reaction was quenched with water and the prepolymer wasprecipitated into methanol to give, after drying, 221 g of a colorlessoil. GPC analysis revealed that the oil was a mixture of about 70%poly(B14-FOX) glycol and 30% cyclic materials.

Example III

This example illustrates the preparation and properties of3,3-bis-(l,1,2,2-tetrahydroperfluorooctylthiomethyl)-3-bromo-1-propanol(see, U.S. Pat. No. 5,097,048).

3,3-bis-(1,1,2,2-tetrahydroperfluoro-octylthiomethyl)oxetane (7.0 g,0.0083 mol) was charged to a three-necked flask with hydrobromic acid(48%, 3.190.018 mol) and toluene (20.0 g). The reaction was heated at100° C. under nitrogen with stirring for 4 h. The water/tolueneazeotrope was then removed at 110° C. The solvent was then removed undervacuum to yield a thick brown liquid which is 99% pure by GLC. NMRshowed proton resonances at 1.80 ppm, 1 proton, (—OH), 2.2-2.6 ppm, 4protons, (2×R _(f)CH₂); 2.7-2.9 ppm, 8 protons, (2×CH ₂SCH₂); 3.53 ppm,2 protons, (CH₂Br); 3.65 ppm, protons, (CH₂OH). Analysis forCH₂₁H₁₇OS₂F₂₆Br: Calculated: C, 27.3%; H, 1.9%, Br, 8.7%, F, 53.5%,7.0%; Found: C, 27.1%, H, 1.7%, Br, 9.1%, F, 51.5%, S, 7.1%.

2. Non-Crystalline Polymers

Examples I-VI illustrate the core of this invention, i.e., that is thecrystalline nature of the bis-substituted oxetane homoprepolymers can bereduced by copolymerization of the bis-substituted oxetane monomers witheither a mono-substituted oxetane monomer, an asymetrically substitutedoxetane monomer or a nonfluorinated cyclic ether, such as THF. Theresulting coprepolymers are amorphous, as indicated by the absence ofcrystallinity in DSC, and thus can be used as soft blocks in preparationof elastomers.

The copolymerization can be conducted in methylene chloride or in THF(in which case THF functions as a reactive solvent). The molecularweight of the coprepolymer is controlled by controlling themonomer:initiator ratio. For example, a monomer:initiator ratio of 20should theoretically lead to a polyether glycol with a degree ofpolymerization (DP) of 20. The initiator used in this process isbutanediol; however, water and variety of other alcohols have also beenused successfully as initiators. Since water also functions veryefficiently as an initiator and is difficult to remove completely, it isimportant to consider water as an initiator along with butanediol inmolecular weight calculation. The amount of water in the monomer andsolvents is easily measured by the Karl Fisher analysis. By propermolecular weight control, macro diols having bewteen 20 and 400 chemicalbonds along the main polyether backbone are obtained that are useful forpreparing elastomers.

The mole ratio of FOX and THF segments in the coprepolymer is easilyestablished by ¹H NMR analysis. However, it is somewhat more difficultto determine the ratio of two FOX comonomers in the coprepolymer by ¹HNMR. However, this ratio can be established by the use of quantitative¹³C NMR. Igated experim ents allow ¹³C-signals to be integratedreliably.

As described above, a preferred catalyst used in preparation of glycolsis BF₃.THF, as the use of this catalyst allows for the preparation ofdifunctional materials. Moreover, a wide variety of initiators can beused. Such, initiators include, but are not limited to, water and thosedescribed above. In addition, a wide variety of solvents can be used.Suitable solvents include, but are not limited to, THF, chlorinatedsolvents, fluorinated solvents, toluene, heptane, tetrahydropyran,verarel (decafluoropentane which is commercially available from DuPont),trifluorotoluene, p-chlorotrifluorotoluene, esters, and the like. In apresently preferred embodiment, THF is used as the solvent, therebyeliminating the use of methylene chloride. Again, however, bothchlorinated and fluorinated solvents can be used for the polymerizationreaction. Preferred temperatures for carrying out the polymerizationreactions range from about 25° C. to about 70° C., with highertemperatures tending to speed up the polymerization reaction.

Example I

This example illustrates the preparation and properties of a 70:30coprepolymer of 3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetaneand tetrahydrofuran [poly(B14-FOX/THF) (70:3 0) glycol].

A solution of butane-1,4-diol (328 mg, 3.64 mmol) and boron trifuloridetetrahydrofuranate (152 mg, 1.08 mmol) in tetrahydrofuran (3.1 g, 43mmol) was stirred at 15° C. or 5 min, under nitrogen, in a drypolymerization flask. Then,3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane (20.0 g, 41.5mmol) was added, and the resulting mixture was stirred at 15° C. for 24h, at which time ¹H NMR analysis of an aliquot indicated that thestarting reagents were essentially unreacted. The solution was warmed to65° C. for 3 h, at which time ¹H NMR analysis of an aliquot indicatedthat the oxtane monomer was consumed. The reaction mixture was quenchedwith water, and the organic layer was separated and added to an equalvolume of methanol. The methanol was decanted and the residual oil wasdried in vacuo at ambient temperature to give 20.5 g (88%) of the titlecoprepolymer, an oil. GPC analysis revealed that the oil contained lessthan 2% cyclic materials. The equivalent weight of this material, asdetermined by ¹H NMR TFAA end group analysis, was 2,879. (It is notedthat in the foregoing analysis, the sample is dissolved indeuterochloroform in an NMR tube and is treated with excesstriflyoroacetic anhydride. The trifluoroacetate of the end groups isformed in situ. The —CH₂— group next to the alcohol is moved 0.5 ppmdown field away from the alcohol and can be integrated against the —CH₂—groups of the ether backbone to determine the equivalent weight.) Thematerial was characterized as follows: DSC: T_(g)=−51° C., no othertransitions observed; GPC: M_(W)=6600, polydispersity index (PDI)=1.7;¹H NMR analysis showed the oil was a 71:29 mole % mixture of B14-FOX andTHF co-monomers.

Example II

This example illustrates the preparation and properties of a 90:10coprepolymer of 3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetaneand tetrahydrofuran having a medium molecular weight [poly(B14-FOX/THF)(91:9) glycol].

A solution of 1,4-butanediol (79 mg, 0.87 mmol) and boron trifluoridetetrahydrofuranate (0.27 g, 1.9 mmol) in methylene chloride (20 mL) wasstirred at ambient temperature for 5 min, under nitrogen, in a drypolymerization flask. Next, a solution of3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane (83.4 g, 173mmol) and tetrahydrofuran (2.5 g, 34.7 mmol) in Freon™ 113 (20 mL) wasadded and the resulting mixture was stirred at ambient temperature for 2days. The progress of the reaction was monitored by ¹H NMR and, oncompletion, the reaction mixture was quenched with water. The organicphase was separated and washed with water and added to an equal volumeof methanol. The methanol layer was decanted and the residual oil wasdried in vacuo at 35° C. to give 72.6 g of the title coprepolymer, anoil. ¹H NMR analysis of the oil revealed that it was a 91:9 mole %mixture of two comonomers,3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane andtetrahydrofuran, respectively. The equivalent weight of thecoprepolymer, as determined by ¹H NMR TFAA end group analysis, was foundto be 14,950. GPC: M_(W)=12,493, polydispersity index (PDI)=1.24, <0.5%cyclic tetramer; DSC: T_(g)=−53° C. The coprepolymer was a colorless oilthat did not crystallize on storage at −20° C. for about 2 months.

Example III

This example illustrates the preparation and properties of a 90:10coprepolymer of 3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetaneand tetrahydrofuran having a low molecular weight [poly(B14-FOX/THF)(90:10) glycol].

A solution of 1,4-butanediol (1.92 g, 21.3 mmol) and boron trifluoridetetrahydrofuranate (0.93 g, 6.6 mmol) in methylene chloride (4 mL) wasstirred at ambient temperature for 5 min, under nitrogen, in a drypolymerization flask. Next, a solution of3,3,-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane (100 g, 207mmol) in Freon™ 113 (20 mL) was added and the resulting mixture wasstirred at ambient temperature for 2 days. The progress of the reactionwas monitored by ¹H NMR and, on completion, the reaction mixture wasquenched with water. The organic phase was separated, washed with water,dried (MgSO₄), filtered and stripped of solvent under reduced pressureto give 114.9 g (97%) of the title coprepolymer, an oil. ¹H NMR analysisof the oil revealed it was a 91:9 mole % mixture of two cocomonomers,3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane and THF,respectively. The equivalent weight of the coprepolymer, as determinedby ¹H NMR TFAA end group analysis, was 1,950: GPC: M_(W)=4175,polydispersity index (PDI)=1.24; DSC: T_(g)=−53° C. The coprepolymer wasan oil and did not crystallize when stored at −20° C. for about 5 weeks.

Example IV

This example illustrates the preparation and properties of a 50:50coprepolymer of 3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetaneand 3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-methyloxetane[poly(B14/7-FOX) (50:50) glycol].

A solution of butane-1,4-diol (791 mg, 8.8 mmol) and boron trifluoridetetrahydrofurnate (373 mg, 2.66 mmol) in methylene chloride (40 mL) wasstirred at ambient temperature for 5 min, under nitrogen, in a drypolymerization flask. Then,3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-methyloxetane (21.5 g, 75.7mmol) and bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane (35.6 g,73.8 mmol) in Freon™ 113 (20 g) was added in bulk, and the resultantmixture was stirred for 64 h at ambient temperature, at which time ¹HNMR analysis of an alliquot indicated that the starting reagents wereessentially consumed. The mixture was quenched with an equal volume ofwater containing 10% sodium bicarbonate. The organic layer was separatedand washed sequentially with aqueous sodium bicarbonate, water andsaturated brine solution. The residue was evaporated in vacuo at 50° C.to give a colorless oil. The oil was stirred for 16 h with hexane (75mL), the hexane layer was decanted and the oil dried in vacuo at 50° C.to give 45 g (79%) of poly(B14/7-FOX) (50:50) glycol, an oil. 13C NMRanalysis (Igated) revealed that the oil was a 50:50 mole % mixture ofB14-FOX and 7-FOX co-monomers. The equivalent weight of thecoprepolymer, as determined by 1H NMR TFAA analysis, was 2,650. Thecoprepolymer was characterized as follows: DSC: T_(g)−51° C.; GPC:M_(W)=5,673 polydispersity index (PDI)=1.7, ¹³C NMR: quaternary carbonsobserved at 41.41 and 46.05; ¹⁹F NMR: −82.02, −121.37, and −128.52.

The coprepolymer was an oil that did not crystallize on extended storage(about 2 months) at −20° C. DSC analysis also revealed that other thanglass transition temperature (−52° C.), no other transitions wereobserved in the temperature range of −80 to 150° C.

Example V

This example illustrates the preparation and properties of a 80:20coprepolymer of 3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetaneand 3-heptafluorobutoxymehtyl-3-methyloxetane [poly(B14/7-FOX) (80:20)glycol].

A solution of 1,4-butanediol (0.55 g, 6.1 mmol) and boron trifluoridetetrahydrofuranate (0.26 g, 1.85 mmol) in methylene chloride (30 mL) wasstirred at ambient temperature for 5 min, under nitrogen, in a drypolymerization flask. Next, a solution of3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane (40.0 g, 82.9mmol) and 3-heptafluorobutoxymethyl-3-methyloxetane (5.9 g, 20.7 mmol)in Freon™ 113 (10.5 mL) was added and the resulting mixture was stirredat ambient temperature for 4 days and at 35° C. for 16 h. The progressof the reaction was monitored by ¹H NMR and, on completion, the reactionmixture was quenched with water. The organic phase was separated andwashed with equal volumes of water, dried (MgSO₄), filtered, andstripped of solvent under reduced pressure to provide 42.4 (91%) of thetitle coprepolymer, an oil: DSC: T_(g)−40° C., no other transitionsobserved; GPC: M_(W)32 4,200, polydispersity index (PDI)=1.25; ¹H NMR(TFAA analysis): equivalent weight=2,050. The ratio of the twocomonomers,3,3-bis-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-methyloxetane and3-heptafluoro-butoxymethyl)-3-methyloxetane, was determined to be 79:21mole % by ¹³C NMR (Igated) analysis.

Example VI

This example illustrates the preparation and properties of a 80:20coprepolymer of 3,3-bis-(2,2,2-trifluoroethoxymethyl)oxetane and3-trifluoroethoxymethyl-3-methyloxetane [poly(B6/3-FOX) glycol].

A solution of 1,4-butanediol (5.5 g, 61 mmoles) and boron trifluoridetetrahydrofuranate (2.5 g, 18.6 mmoles) in methylene chloride (150 mL)was stirred at ambient temperature for 15 mins. Next, a solution of3,3-bis(2,2,2-trifluoroethoxymethyl)oxetane (227 g, 805 mmol) and3-trifluoroethoxymethyl-3-methyloxetane (38.3 g, 208 mmol) in Freon™ 113(30 mL) was added, and the resulting mixture was stirred at ambienttemperature for 1 day and at reflux for 2 days. The progress of thereaction was monitored by 1 H NMR and, on completion, the reactionmixture was quenched with water. The organic phase was separated andwashed with water, dried (MgSO₄), filtered and stripped of solvent underreduced pressure to give 253 g (95%) of the title coprepolymer, acolorless oil. The ratio of two co-monomeric unis,3,3-bis(2,2,2-trifluoroethoxymethyl)oxetane and3-trifluoroethoxymethyl-3-methyloxetane, was determined to be 82:18 mole% by 13C NMR (Igated) analysis. The equivalent weight, as determind by1H NMR TFAA analysis, was found to be 2,164.

Example VII

This example illustrates the preparation and polymerization of a 70:30coprepolymer of M6-14-FOX and tetrahydrofuran [poly(M6-14-FOX/THF)(70:30) glycol].

A solution of butane-1,4-diol (3.6 mmol) and boron trifluroidetetrahydrofuranate (1.08 mmol) in 3.1 g of tetrahydrofuran was stirredat 15° C. for 5 min, under dry nitrogen, in a polymerization flask.M6-14-FOX (20.0 g) was added to the mixture and stirred at 15° C. for2.5 h, then heated to 65° C. for 3 h. ¹H NMR analysis of an aliquotindicated that the monomers were consumed. The reaction was quenchedwith an excess of water, the organic layer was separated and thecoprepolymer separated by addition of an equal volume of methanol. Afterseparating the methanol, the residual polymer oil was vacuum dried. GPCanalysis revealed less than 2% cyclic materials. The equivalent weightof the glycol, as determined by ¹H NMR TFAA end group analysis, was3,000. The material exhibited a T_(g) of −52° C. and no othertransitions. GPC showed a polydispersity index (PDI) of 1.8.

3. Exemplar Coprepolymers

Using the methods described herein, bis-substituted FOX monomers werecopolymerized with mono-substituted FOX monomers and THF. Examplarcopolymers are set forth in Table 3.

TABLE 3 Copolymerization of Bis-substituted oxetane monomers MonomerMonomer Feed A:B Mole Ratio (A:B) M_(w) A B Ratio (mole) in Coprepolymer(GPC) Yield B14-FOX THF 46:54 71:29 6,600 88% B14-FOX THF 69:31 91:9 12,493 85% B14-FOX THF 88:12 91:9  4,175 97% B14-FOX 7-FOX 80:20 80:204,100 91% B14-FOX 7-FOX 50:50 50:50 5,673 79%

The properties and characteristics of the various coprepolymers werestudied. As set forth in Table 4, both the coprepolymers formed frombis- and mono-substituted FOX monomers and from bis-substituted FOXmonomers and THF are non-crystalline, i.e., they are amphorous oils.

TABLE 4 Poly(FOX) Glycols Based on Bis-Substituted Oxetanes B6-FOXB14-FOX B14/7-FOX B14/7-FOX B14/THF B14/THF B14/THF Ratio of Co- 100  100 50:50 80:20 71:29 91:9 91:9 monomers Physical State Wax Wax OilOil Oil Oil Oil Eq. Wt. — — 2,650 2,052 1,950 7,474 (NMR) GPC:M_(w)27,071   9,047 5,673 4,175 3,811 12,493  M_(w)/M_(n)   2.2     1.4    1.73     1.25     1.27     1.24 DCA:θ_(adv)  104.0 — — — — — —θ_(rec)   89.3 — — — — — — DSC mp ° C. 71.7° C. ND* ND* ND* ND* ND* ΔHm26.3 J/gm ND* ND* ND* ND* ND* T_(g) ° C. −39   −52   −49 −51   −53   −53*Not Determined.

D. Polyurethanes

Example I

This example illustrates the preparation and properties of athermoplastic polyurethane prepared from poly(B14/7-FOX) (50:50) glycol.

A 50 mL three-necked flask was dried under argon and charged withpoly(B14/7-FOX) (50:50) glycol (3.42 g, 1.28 mmol, equivalent weight2650), IPDI (464 mg, 4.05 mmol), LV-33/T12 catalyst in THF (62 mg), andTHF (5 mL). The mixture was heated to reflux for 3.5 h, and then1,4-butanediol (BDO) (111 mg, 2.47 m equiv) dissolved in THF (0.5 mL)and DMAC (1.5 mL) was added. The heating was continued for 3 h and themixture was cooled to ambient temperature. The solution was used to dipcoat glass slides. The slides were dried in an oven at 65° C. to give asmooth, colorless, tack-free coating. The coatings were analyzed by DCAand were found to exhibit an advancing contact angle of 127 degree and areceding contact angle of 41 degrees with water. The polyurethane wasisolated by precipitating the polymer solution in methanol andcollecting the precipitated material by filtration. The filteredmaterial was dried in a vacuum oven at 40° C. for 16 h to give 3.72 g(86%) of the title polymer, a tack-free elastomer: GPC: M_(W)=25,532,polydispersity index (PDI)=3.1; DSC: T_(g) =−47° C.

Example II

This example illustrates the preparation and properties of athermoplastic polyurethane prepared from poly(M6-14-FOX/THF) (70:30)glycol.

A 100 mL three-necked flask was dried under argon and charged with 38.76mmol of MDI and 10 mL DMAC. The mixture was heated to 60° C. and asolution of poly(M6-14-FOX/THF) (70:30) glycol (3.1 mmol) and dibutyltindilaurate catalyst (48 mg) dissolved in 10 mL of THF was added. Afterreacting at 60° C. for 2 h, 34.86 mmol of 1,4 butanediol in 1 mL THF wasadded. 10 mL DMAc was added and the reaction was continued for 20 h at65° C. After cooling to room temperature, 400 mL methanol was added toprecipitate the polymer which was collected and dried. The polyurethaneelastomer was dissolved as a 10 wt. % solution in DMAc and used to coatvarious substrates to give elastomeric tack-free castings. GPC analysisgave a M_(W) of about 85,000 and a polydispersity index (PDI) of 2.4.DSC showed a T_(g) at −50° C. and melting point of the hard segment at200° C. to 230° C. DCA(H₂O): θ_(adv)=120 deg, θ_(rec)=68 deg.

The increase in M_(W) as measured by GPC from M_(W)=5,600 to 25,500shows that there is hydroxyl functionality on at least 85% of the chainends.

Example III

This example illustrates the preparation and properties of athermoplastic polyurethane prepared from poly(B14/7-FOX) (80:20) glycol.

A 100 mL three-necked flask was dried under argon and charged with MDI(4.923 g, 38.76 mmol) and DMAC (10 mL). The mixture was heated to 65° C.and a solution of 80:20 poly(B14/7-FOX) glycol (6.4 g, 3.1 mmol,equivalent weight 2,052) and dibutyltin dilarate catalyst (48 mg)dissolved in THF (10 mL) was added. The mixture was heated at 65° C. for1.5 h and treated with a solution of 1,4-butanediol (1.571 g, 34.86mmol) in THF (1.0 mL). DMAC was added and the resulting mixture washeated at 65° C. for 20 h. The reaction mixture was cooled to ambienttemperature and added to methanol (400 mL). The precipitated polymer wascollected by filtration and dried in a vacuum oven at 40° C./30 mm/Hg/16h to give 10.9 g (85%) of the title polyurethane, a white elastomer. Thepolyurethane elastomer was dissolved in DMAC (10% wt.) and the resultinglacquer was used for coating applications. Substrates, such as wood,glass, leather, rubber (EPDM rubber), fiber glass, stainless steel (304and 316 SS), aluminum and fabrics, were coated with this solution andplaced in an oven at 65° for 16 h. The resulting coatings were tack-freeand elastomeric. The polyurethane was characterized as follows: DCA(H20): θ_(adv)=116 deg, θ_(rec)=68 deg; Surface Energy: 11.7 dynes/cm;GPC: M_(W)=83,657, polydispersity index (PDI) =2.34; DSC: T_(g)=−47C.,melting endotherms at 208 and 225° C.

The increase in M_(W) as measured by GPC from M_(W)=4,200 to 84,000shows that there is hydroxyl functionality on at least 95% of the chainends.

Example IV

This example illustrates the preparation of a thermoset polyurethaneelastomer prepared from poly(B14/7-Fox) (80:20) glycol.

Poly(B14/7-Fox) (80:20) glycol (12.8 g, 6.2 meq, equivalent weight2,052) was mixed with ISONOL-93 (1.08 g, 12.4 meq), and dibutyltindilaurate (2 mg)in a beaker at 60° C. Des-W (2.60 g, 19.8 meq) was addedand the mixing was continued at 60° C. for 15 mins, after which thecontents were transferred into a TEFLON™ mold. The mold was placed in avacuum oven and degassed (100° C. at 29 inch vacuum for 30 mins). Themixture was then cured at 65° C. for 46 h to give a tack free elastomer.

Example V

This example illustrates the preparation of a thermoset polyurethaneelastomer prepared from poly(B14/7-FOX) (50:50) glycol.

Poly(B14/7-FOX) (50:50) glycol (13.68 g, 5.16 meq, equivalentweight=2,650) was mixed with ISONOL-93 (0.90 g, 10.3 meq), anddibutyltin dilaurate (3 mg)in a beaker at 60° C. Des-W (2.13 g, 16.2meq) was added and the mixing was continued at 65° C. for 10 mins, afterwhich the contents were transferred into a TEFLON™ mold. The mold wasplaced in a vacuum oven and degassed (100° C. at 29 inch vacuum for 30mins). The mixture was then cured at 65° C. for 36 h to give a tack-freeelastomer.

Example VI

This example illustrates the preparation and preparation of a thermosetpolyurethane elastomer from poly(B14-FOX/THF) (90:10) glycol.

A 500 mL round-bottom three-necked flask was dried and assembled underargon with a condenser, thermacouple probe and magnetic stirring. Theapparatus was charged sequentially with anhydrous dichloromethane (80mL), 1,4-butanediol (1.9196 g, 21.3 mmol), boron trifluoridetetrahydrofuranate (0.9289 g, 6.64 mmol), and3,3-bis(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane (118.20 g, 0.245mol) in Freon™ 113 (40 mL). The solution was stirred at ambienttemperature for 48 h at which time proton NMR analysis indicated that95% of the monomer had been consumed. The reaction was quenched withaqueous sodium carbonate (50 mL), separated, and the organic phase waswashed with aqueous hydrochloric acid (10%, 2×75 mL), water and brine.The organic solution was dried with magnesium sulfate and evaporated invacuo to give 111.8 g (95%) of the prepolymer as a clear liquid. Thecrude polymer was found to have a molecular weight of 4,050 and M_(W)/Mnof 1.25 by GPC and to contain less than 10% of low molecular weightoligomers. Proton NMR analysis showed the ratio of oxetane totetrahydrofuran was 9.6 mole %. The equivalent weight was 1,948. 1H NMR1.67 (s, 0.04 H), 1.85 (m, 0.03 H), 2.2 (m, 0.03 H), 3.44 (s, 4 H), 3.63(m, 4 H), 3.88 (m, 4H).

Example VII

This example illustrates exemplar properties of the polyurethanes of thepresent invention. More particularly, Table 5 sets forth the propertiesof the polyurethanes prepared from the coprepolymers of the presentinvention.

TABLE 5 Polyurethanes from coprepolymers B14/7-FOX B14/7-FOX B14/THFRatio of comonomers 50:50 80:20 91:9 Curative IPDI/BDO MDI/BDO MDI/BDOState Elastomer Elastomer Elastomer % Hard Segment 15% 50% 50% GPC:M_(w) 25,532 83,657 22,656 M_(w)/M_(n) 3.1 2.34 2.36 DCA: θ_(adv) 126116.2 115.9 θ_(rec) 41 67.5 68.4 Surface Energy 9.8 dynes/cm 11.7dynes/cm — DSC T_(g) ° C. −47 −47 & +105.4 −51 & +113 MP ° C. ND* 208and 225 188 ΔHm (J/g) ND* 36.1 ND* *Not Determined.

E. Structure

Table 6 sets forth the ¹³C NMR comparison of homo- and coprepolymersprepared using mono- and bis-substituted oxetanes. In addition, thecopolymer of 7-FOX and B14-FOX was subjected to quantitative carbon(¹³C) NMR spectroscopy using Igated decoupling techniques (see, Table7). The quaternary carbons at 41.41 bearing one fluorinated group and amethyl group and at 46.05 due to the bis-fluorinated substituants wereintegrated and found to correspond to a ratio of 50.6 to 49.4. This isthe correct ratio based on the monomer feeds for the copolymer. Thesignals from the quaternary carbons in the copolymers also appear astriads as expected for a random copolymer in which each one of twodissimilar monomers may appear adjacent to either similar to dissimilarmonomers in the polymer backbone resulting from arrangements of AAB, BABor AAA.

TABLE 6 ¹³C NMR Comparison of Homo- and Coprepolymers of Mono- andBis-substituted Oxetanes Quaternary Prepolymer Carbons —CH₃ —CH_(2-R)fOther Poly-7-FOX 41.77 17.22 68.68 74.30, 75.95 Poly B14-FOX 46.24 -68.45  70.0, 71.95 Copoly 7/B14-FOX 41.41 & 46.05 17.04 68.30 Many peaks

TABLE 7 Igated ¹³C NMR Experiments of B14- and 7-FOX Copolymers Wt. %Found in Product by Copolymer Wt. % of Monomers in Feed Igated 13C NMRB14/7-FOX 50:50 50.6:49.4 B14/7-FOX 80:20 79.4:20.6

It is to be understood that the above description is intended to beillustrative and not restrictive. Many embodiments will be apparent tothose of skill in the art upon reading the above description. The scopeof the invention should, therefore, be determined not with reference tothe above description, but should instead be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled. The disclosures of all articles andreferences, including patent applications and publications, areincorporated herein by reference for all purposes.

What is claimed is:
 1. A hydroxy-terminated FOX prepolymer comprising amonomeric unit having the general formula:

wherein: each n is independently selected and is 1 to 3; R_(f) ¹ andR_(f) ² are independently selected from the group consisting of linearperfluorinated alkyls, linear perfluorinated isoalkyls, branched chainperfluorinated alkyols, branched perfluorinated isoalkyls, saidperfluorinated alkyls and isoalkyls having from 1 to about 20 carbonatoms, and oxaperfluorinated polyethers having from 4 to about 60 carbonatoms; and x is 1 to about 250; with the proviso that R_(f) ¹ and R_(f)² are different.
 2. A hydroxy-terminated FOX prepolymer in accordancewith claim 1, wherein R_(f) ¹ and R_(f) ² are both linear perfluorinatedalkyls.
 3. A hydroxy-terminated FOX prepolymer in accordance with claim2, wherein said FOX prepolymer ispoly(3-(2,2,2-trifluoroethoxymethyl)-3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane).4. A hydroxy-terminated FOX prepolymer in accordance with claim 2,wherein said FOX prepolymer ispoly(3-(2,2,2-trifluoroethoxymethyl)-3-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxymethyl)oxetane).5. A hydroxy-terminated FOX prepolymer in accordance with claim 2,wherein said FOX prepolymer ispoly(3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyloxymethyl)oxetane).6. A hydroxy-terminated FOX prepolymer in accordance with claim 2,wherein said FOX prepolymer ispoly(3-(2,2,2-trifluoroethoxymethyl)-3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyloxymethyl)oxetane).7. A hydroxy-terminated FOX prepolymer in accordance with claim 2,wherein said FOX prepolymer ispoly(3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorodedecyloxymethyl)oxetane).8. A hydroxy-terminated FOX prepolymer in accordance with claim 2,wherein x is from about 10 to about
 50. 9. A hydroxy-terminated FOXcoprepolymer comprising a mixture of monomeric units having the generalformulae:

wherein: each n is independently selected and is 1 to 3; R is selectedfrom the group consisting of methyl and ethyl; R_(f) ¹, R_(f) ² andR_(f) ³ are independently selected from the group consisting of linearfluorinated alkyls, linear fluorinated isoalkyls, branched chainfluorinated alkyls, branched fluorinated isoalkyls, said fluorinatedalkyls and isoalkyls having from 1 to 20 carbon atoms, andoxaperfluorinated polyethers having from 4 to about 60 carbon atoms; xis 1 to about 250; and y is 1 to about
 250. 10. A hydroxy-terminated FOXprepolymer in accordance with claim 9, wherein R_(f) ¹, R_(f) ² andR_(f) ³ are linear perfluorinated alkyls.
 11. A hydroxy-terminated FOXcoprepolymer in accordance with claim 9, wherein R_(f) ¹ and R_(f) ² arethe same.
 12. A hydroxy-terminated FOX coprepolymer in accordance withclaim 9, wherein R_(f) ¹ and R_(f) ² are different.
 13. Ahydroxy-terminated FOX coprepolymer in accordance with claim 9, whereinsaid hydroxy-terminated FOX coprepolymer is produced from thepolymerization of at least one bis-substituted FOX monomer selected fromthe group consisting of 3,3-(2,2,2-trifluoroethoxymethyl)oxetane,3,3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane,3,3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyloxymethyl)oxetane,3,3-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxymethyl)oxetane,3,3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyloxymethyl)oxetane,3,3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorododecyloxymethyl)oxetane,3-(2,2,2-trifluoroethoxymethyl)-3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetaneand3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyloxymethyl)oxetane,with at least one mono-substituted FOX monomer selected from the groupconsisting of 3-(2,2,2-trifluoroethoxymethyl)-3-methyloxetane,3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-methyloxetane,3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyloxymethyl)-3-methyloxetane,3-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxymethyl)-3-methyloxetane,3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,-10,10-heptadecafluorodecyloxymethyl)-3-methyloxetane,and3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,-10,10,11,11,12,12,12-heneicosafluorododecyloxymethyl)-3-methyloxetane.14. A hydroxy-terminated FOX coprepolymer in accordance with claim 13,wherein said bis-substituted FOX monomer is3,3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane, and saidmono-substituted FOX monomer is3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-methyloxetane.
 15. Ahydroxy-terminated FOX coprepolymer in accordance with claim 13, whereinsaid bis-substituted FOX monomer is3,3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)oxetane, and saidmono-substituted FOX monomer is3-(2,2,2-trifluoroethoxymethyl)-3-methyloxetane.
 16. Ahydroxy-terminated FOX coprepolymer in accordance with claim 13, whereinsaid bis-substituted FOX monomer is3,3-(2,2,2-trifluoroethoxymethyl)oxetane, and said mono-substituted FOXmonomer is 3-(2,2,2-trifluoroethoxymethyl)-3-methyloxetane.
 17. Ahydroxy-terminated FOX coprepolymer in accordance with claim 9, whereinthe ratio of said bis-substituted FOX monomer to said mono-substitutedFOX monomer is in the range of from about 50:50 to about 95:5.